CLASS XII Competency Focused Practice Questions Chemistry (Volume 1)
CLASS XII Competency Focused Practice Questions Chemistry (Volume 1)
CLASS XII Competency Focused Practice Questions Chemistry (Volume 1)
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Team CBSE
Q.1 The equivalent mass of KMnO4 in acidic medium is less than that in neutral 2
medium. Explain.
In acidic medium,
In neutral medium,
Thus, the equivalent mass of KMnO4 in acidic medium is less than that in neutral
medium.
[Give 1 mark each for the calculation of equivalent weight in acidic and neutral
medium.]
:
(i) Identify the ion(s) moving towards the cathode. Give a reason for your choice.
(ii) What is the expected product at the anode? Write the reaction(s) occuring at
the anode.
(iii) Write the net reaction of the process seen in the above diagram.
(iv) State the laws that govern the above process.
(i) What are the product(s) formed at the cathode for the given setup? What
factors did you consider to determine the products of electrolysis in the cell given
above?
(ii) What is the nature and function of the electrodes seen here?
(iii) Write the electrode reactions if the electrolyte is changed to molten sodium
chloride.
E = E° -(0.059/2) log[A+2/[B+]2]
= 3.17-0.1652
= 3.0047 V
[ Give 1 mark for the correct substitution and 1 mark for the correct answer]
Q.3 (i) The ions moving towards the cathode are Na+. The electrolyte is molten 5
sodium chloride, so only one cation (Na+) is present in the reaction medium.
[Give 0.5 marks for correctly identified ion and 0.5 marks for the reason.]
[Give 0.5 mark for the correctly identified product formed at the anode and 0.5
marks for the anode reaction.]
(iv) The above process is governed by the Faraday's law of electrolysis. They are
as follows:
Q.4 (i) The product formed at the cathode for the above reaction is sodium 5
hydroxide(NaOH) and hydrogen(H2).
(a) The products of electrolysis depend on the different oxidising and reducing
species present in the electrolytic cell and their standard electrode potentials.
[Give 0.5 marks for each correctly mentioned products.Give 1 mark for each
correctly mentioned points. The students may write the answer in their own
words]
(ii) The nature of the electrodes are inert. The electrodes do not participate in
the chemical reaction but acts only as source or sink for electrons.
[Give 0.5 marks for identifying the nature of the electrode and 0.5 marks for
writing the function of the electrode.]
Q.5 Which of the following is the unit of the rate constant for a zero order reaction? 1
A. s-1
B. mol L-1
C. mol L-1 s-1
D. L mol-1 s-1
Q.6 Which of the following graphs represents a zero order rate of reaction? 1
A. A
B. B
C. C
D. D
Q.6 C. C 1
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) correct but (R) is not the correct explanation of (A)
C. (A) is correct, (R) is wrong
D. Both (A) and (R) are wrong
Q.8 Shweta was conducting an experiment in the chemistry lab. She took two similar 2
glasses- one filled with cold water and one filled with hot water. In each of the
glasses, she added the same amount of ink and noted her observations after 10-
20 seconds.
She observed the following results in these glasses:
Q.11 Compare the effectiveness of the coagulation of Al(OH)3 sol in the presence 2
of K3PO4 and the coagulation of Al(OH)3 sol in the presence of NaCl. Also, state
the reason behind the difference between the two cases.
Q.7 B. Both (A) and (R) correct but (R) is not the correct explanation of (A) 1
(ii) Since Glass 1 is filled with hot water, the speed of Brownian motion in hot
water is higher than that in cold water which makes it difficult for ink particles to
settle at the base and coagulate.
- With the increase in the concentration of substrate, more enzymes can link with
substrate molecules, and the rate increases [0.5]
- Once all enzymes are used up, the rate can't increase further and becomes
constant. [0.5]
Graph: [1]
Give 1 mark if the basic pattern of the graph is the same even without values. But
labelling of axes should be there
- When the inhibitor molecules are very similar to the substrate, the enzyme
molecules can't distinguish among them and this leads to the competition [0.5]
Q.11 - Compared to NaCl, K3PO4 is more effective for the coagulation of Al(OH)3 sol. 1
Reason:
- As per the Hardy-Schulze rule, for a positively charged sol (Al(OH)3 sol) anion
with the maximum charge would be the most effective for coagulation.
Hence, K3PO4 (with 3 units of -ve charge) is more effective than NaCl (with 1 unit
of -ve charge)
IV) with a small amount of crushed ore, the yield of products is higher.
Which of the options are LIKELY to be the most appropriate reasons for crushing
of an ore?
A mixture of two ores of transition metals, A and B are passed over a conveyer
Q.14 1
belt. The following inferences were drawn from the given diagram.
Q.15 Two statements are given below - one labelled Assertion (A) and the other 1
labelled Reason (R).
Assertion (A): Arkel Method for Refining is a type of vapour phase refining.
Reason (R): This method is useful for producing semiconductors and other
metals of high purity.
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
Two statements are given below - one labelled Assertion (A) and the other
Q.16 1
labelled Reason (R).
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
(a) Among the ions that migrate towards the cathode which has the lowest
reduction potential? Is it discharged at the cathode?
(b) 'In Hall-Heroult’s process the anode has to be replaced from time to time.'
(a) Which of the following ore(s) can be concentrated by the above method?
(b) What inference can be drawn from points B and C on the graph?
A certain form of iron is used for casting railway sleepers. This form of iron is a
Q.20 3
little hard and brittle.
(b) Name the forms of iron that can be made using the form of iron mentioned
in (a)?
A sample of a dye of a flower consists of three components a,b,and c. The sample
Q.21 2
is dissolved in a suitable solvent and the solution is then poured into the
apparatus shown below that contains a solid stationary phase.
Arrange the three components of the dye in the increasing order of their affinity
for the stationary phase. Give a reason for your answer.
(b) Four strips of pure copper, after the purification process, are placed in four
different colourless salt solutions of NaNO3, ZnSO4, AgCl, and HgCl2. Which of the
solution(s) will not show any observable change?
(a) Identify the process of concentration shown in the image given below:
Q.23 3
(a) In the Gibbs energy (ΔG-) vs T plots which element occupies the highest
position among M, N, and coke?
(b) Which of the metals, M and N is MOST LIKELY to be Cu and the Mg?
(a) Suggest the most suitable way of benefaction that can be followed to get a
cleaner sample of the metal from the gold block that she had.
(b) Identify/name the solution and state the reaction condition that may be used
to dress the ore.
(c) Represent the above reaction with the help of a chemical equation.
(a) Which metal block will undergo corrosion in the given setup?
(b) What can be the most suitable electrolyte for the process?
(d) How can we utilize substance 'X' to make this process cost-effective?
(e) Name an alloy formed only by this metal, with another metal that can be
refined by this process
Q.17 (i) Ca+2 ion has the lowest reduction potential. No, it is not discharged at the 2
cathode.
[Give 0.5 marks for each correct answer]
(ii) The above statement is justified by the following reactions:
Q.18 (a) The ore(s) that can be concentrated by the above method are copper glance 2
and Sphalerite.
(b) The mineral particles are preferentially wetted by pine oil rather than in
water while the gangue particles are wetted by water. This helps in the
concentration of the mineral ore.
(a) (Mg, MgO) plot is a straight line except when some phase change occurs. The
Q.19 2
temperature at which such change occurs is indicated by an increase in the slope
on the positive side.
(b) From points B and C, we can infer that ZnO can be reduced to Zn by carbon
monoxide and carbon dioxide.
(b) The other two forms of iron that can be made from cast iron is wrought iron
and alloy steel.
The components in the increasing order of their affinity for the stationary phase
Q.21 2
Component c< Component b< Component a
This is because a component which has a greater affinity for the stationary phase
takes a longer time to travel through it than a component that has less affinity
for the stationary phase.
[Give 1 mark for the correct order and 1 mark for the reason.]
Q.22 (a) In the electrolytic refining of copper anodes are of impure copper and pure 3
copper strips are taken as cathode. The colour of the electrolyte is blue due to
the presence of Cu+2ions. The colour of the electrolyte in this process remains
blue due to there is a continuous flow of Cu+2 from anode after impure copper
ions in the solution.
(b) Two solutions will not show any observable change. They are AgCl and HgCl2.
(a) Metal M occupies the highest position in the Gibbs energy (ΔG-) vs T plots
Q.24 3
among these three elements.
Q.25 (a) The most suitable method of benefaction that can be followed is Leaching. 4
(b) The solution needed to carry out the process is either sodium cyanide or
potassium cyanide in the presence of excess of air or oxygen.
[Give 1 mark for any of the two solutions and 1 mark for the reaction conditions.]
(a)Give 0.5 marks each for the correct answer. No marks if copper is not
Q.27 5
mentioned.
(c)
- Some impurities from the impure block of copper get dissolved in the acid while
some remain insoluble. The insoluble impurities get collected at the bottom of
the anode as anode mud. [0.5 marks]
(d) Recovery of the impurities like antimony, selenium, tellurium, silver, gold and
platinum helps in meeting the cost of refining.
Q.28 Which one of the following effects does V2O5 have on the equilibrium of the 1
following reaction?
Q.29 The image shows the flow diagram for the formation of sulfuric acid through 1
contact process.
Which of the following explains the use of heat exchangers in the converter in
stage 2?
A. Only ii
B. Only i and ii
C. Only iii and iv
D. All of them
Q.30 Which of the following rows correctly shows the effect of plunging a similar red- 1
iron hot rod into different hydrogen halides?
decomposes decomposes
A unaffected
completely completely
decomposes slightly
B unaffected
completely decomposes
decomposes
C unaffected unaffected
completely
decomposes slightly
D unaffected
completely decomposes
A. A
B. B
C. C
D. D
Q.31 The graph below shows the first two ionization enthalpies of four elements A, 1
B, C, and D (the letters are not their chemical symbols). These elements are the
first two elements of groups 15 and 16. Which element is Oxygen?
(Q) Both ClI3 and ClBr can be prepared by direct combination of halogens.
(R) The angle between two adjacent Br-F bonds (bond angle) in BrF3 is 900.
A. P and Q only
B. P and R only
C. Q and R only
D. P only
Q.33 The burning of a match stick is based on the chemistry and the reaction 1
involved with phosphorous.
Which of the following correctly maps out the parts of the matchbox with the
type of phosphorus used?
Q.34 The standard enthalpy changes of formation of HCl and HI are -92 and +26 1
kJmol-1. Which of the following statements is the most important in explaining
this difference?
A. The activation energy for the decomposition of HI is smaller than that for
HCl.
B. The bond energy of H-I is smaller than that of H-Cl.
C. The bond energy of I-I is smaller than that of Cl-Cl.
D. The acidic nature of HI is greater than that of HCl.
A. only Cl-
B. only I-
C. only Br- and I-
D. all- Cl-, Br-, I-
Q.36 Which of the following reactions of halide with another halide ion from a salt 1
solution is/are possible?
A. i only
B. iii only
C. i and iii only
D. all- i, ii, and iii
The table below shows a reactant and a product from different redox reactions
involving halogens and their compounds.
Reactant Product
A 2Cl− Cl2
B Cl− ClO−
C ClO3− Cl2
D ClO− ClO3−
A. A
B. B
C. C
D. D
Q.38 How many of the changes in the table are examples of oxidation? 1
A. 1
B. 2
C. 3
Q.39 Which of the following is the BEST way to identify the presence of iodine in an 1
aqueous solution?
Q.41 (i) Explain with the help of chemical reactions why Phosphine is important for 4
producing signals in sea?
Q.42 Heating halogen halides to same temperature has the following effects. 2
-HI decomposes.
-HBr shows some evidence of decomposition.
-HCl is unaffected.
What do you think the effect of heating would be on HF? Explain your answer.
(i) Why does conc. H2S04 produce Br2 gas on reacting with solid halide while
conc. H3PO4 does not?
(ii) Why does conc. H2S04 not produce any chlorine gas (Cl2) or fluorine (F2)
when it reacts with solid chloride or solid fluoride respectively?
Q.44 The table below shows the equation and description of reactions of hydrogen 3
and the halogens.
Astatine (At) lies below iodine at the bottom of group 17. Based on the above
table, write down:
(ii) thermal stability of its hydride. Also give reasons behind your answer.
Q.45 Alika found an unknown solid compound in a chemistry lab. She made a 2
hypothesis that the compound is potassium bromide. How should she test her
hypothesis and get a positive result if her hypothesis is correct?
Q.46 Sulphur is a group VI element whose highest oxidation number is +6. Which 0.5
halogen, X can be used to form SX6 and why?
Q.47 The below table shows the nine most plentiful components of the atmosphere 2
by mass. Over 98% is nitrogen and oxygen, but the noble gas argon comes third,
making up over half the residue.
The discovery of the noble gases was initiated when, in 1892, Lord Rayleigh
noted that atmospheric nitrogen obtained by the removal of oxygen, CO2 and
water vapour from air was slightly denser (1.2572 g/litre) than chemically
prepared nitrogen (1.2505 g/litre). Which undiscovered element do you think
was mainly responsible for this discrepancy? Why?
Q.49 The table below shows standard enthalpies of formation of some noble gas 4
compounds at room temperature.
Q.50 (i) Sodium chloride and sodium iodide are both compounds which contain 3
halide ions. Silver nitrate solution may be used to differentiate between
solutions of sodium chloride and sodium iodide. Write the observations that
would be expected in both cases.
(ii) Chlorine produces a range of oxoacids, including chloric(I) acid, HOCl, and
chloric (VII) acid, HClO4. Which amongst them is the strongest acid?
Q.51 The table below shows the boiling point of some of the compounds: 2
(i) Explain why the boiling point of HI is higher than that of HBr.
(ii) Why H2O has a higher boiling temperature than HF?
Q.53 (i) Explain why traces of sulfur dioxide are emitted from oil burning furnaces? 2
(ii) Write an equation to show how one of the following substances could be
used to reduce the sulfur dioxide in part a: CaCl2, CaSO4, Ca(OH)2.
Q.54 When chlorine gas reacts with cold and dilute sodium hydroxide, they form A, 2
B, and water as products. But, when the chlorine gas reacts with hot and conc.
sodium hydroxide, they form A, C, and water as products.
(b) Which among A, B, and C has the highest positive oxidation number of the
central atom.
Q.57 (i) In order to obtain metallic silver from its nitrate, why can we not use 2
orthophosphoric acid(H3PO4)?
(ii) It is found that platinum spokes used in bikes or cycles do not corrode in the
presence of air or moisture. Justify.
Q.58 Why do the precipitates of AgCl and AgBr dissolve in ammonia? Explain with the 2
help of reactions.
Q.59 David has a solution that contains bromide ions. He goes inside a lab and carries 2
out these steps:
Step 1: bubbles chlorine gas through a sample of the solution. The mixture
changes colour.
Step 2: adds cyclohexane to the mixture and then shakes the mixture and allows
the layers to seperate.
(i) Write the ionic reaction for step 1.
(ii) What will be the final color of cyclohexane layer in step 2?
Q.60 Chlorine is toxic to humans. This toxicity does not prevent the large scale use of 3
chlorine in water plants.
(i) Give one reason why water is treated with chlorine.
(ii) Explain why the toxicity of chlorine does not prevent this use.
(iii) Write an equation for the reaction of chlorine with cold water.
Q.30 B. B 1
Q.31 C. C 1
Q.32 D. P only 1
Q.37 C. C 1
Q.38 C. 3 1
Q.40 (i) When the white phosphorus is heated, one of the bonds between two atoms 2
in a discrete tetrahedral is broken. This enables the phosphorous to form a chain
of tetrahedral, maintaining the same bond order for each atom
(ii) Red phosphorus has a polymeric structure which makes it extra stable [0.5]
- Unlike white phosphorous, its bond angle is higher than that of white
phosphorous which causes less strain and makes it more stable [0.5]
Q.41 (i) Signals are produced as a part of two stage reaction. In stage 1, calcium 4
phosphide reacts with water to give Phosphine. Also, calcium carbide reacts with
water to give acetylene gas.
- Ca3P2+6H2O→2PH3+3Ca(OH)2 [1]
- CaC2 + 2H2O→C2H2 + Ca(OH)2 [1]
- In stage 2, due to impurities of P2H4 present in phosphine, it reacts with oxygen
in a combustion reaction and burns up. [0.5]
- The heat obtained in this process also burns acetylene, due to which it seems
like the ocean is on fire. [0.5]
- HF has the strongest bond in the group. Since, HCl is unaffected, HF will
definitely be unaffected as it requires more energy to break HF bond [1]
Q.43 (i) When H2S04 reacts with solid bromide, it produces HBr(g). However, as H2S04 3
is a powerful oxidising agent it oxidises HBr to Br2. [1]
-Conc. H3PO4 on the other hand is not a strong oxidising agent and hence does
not oxidise HBr(g) to Br2. [1]
(ii) Concentrated sulfuric acid is not a strong enough oxidizing agent to oxidize
fluoride or chloride. In terms of the halide ions, unlike bromides and iodides,
fluorides and chlorides are not strong enough reducing agents to reduce the
sulfuric acid.
(ii) Hydrogen astatine will be the least thermally stable in group 17. [1]
- This is because the astatine atom is the largest atom, so the overlap of its outer
shell with a hydrogen atom gives a much longer bond length than with the other
smaller halogen atoms. The longer the bond, the weaker it is, and the less energy
required to break it. [1]
- If a reddish-brown gas is seen, it means Br2 is being released. If this does not
happen then her hypothesis is wrong [1]
- She can infer that conc. sulfuric acid gives hydrogen bromide in the first stage
of the reaction. Since HBr decomposes easily with strong oxidising agent, HBr
changes to Br2 quickly. [1]
Note give full marks if students uses AgNO3 in place of conc. sulfuric acid and
writes formation of pale yellow solid.
- Fluorine is small in size, has high electronegativity and hence it can oxidise the
metal to its highest oxidation state. [1]
Reason:
- Of the noble gases, argon is the most abundant. Its molar mass (40) is also
higher than that of N2 (28), so the presence of argon in nitrogen tends to raise
the density. [1]
Q.48 (i) As we go down the group, the distance between electrons and nucleus 2
increases which increases polarizability down the group. Hence the electron
cloud is loosely bond [1]
(ii) The induced dipole-induced dipole interactions that hold the atoms together,
increase with polarizability. Thus, the melting and boiling temperatures increase
down the group as the ionization energy decreases. [1]
Q.49 (i) XeO4; because ΔHf- is positive for XeO4. It will decompose even at room 4
temperature
(ii) No; The positive value of ΔHf- suggests not; formation from the standard
states Kr(g) and F2(g) is thermodynamically unfavourable at room temperature
Q.51 (i) (Iodine/HI) has more number of electron shells. So, more energy is needed to 2
separate molecules with a stronger London force.
(ii) Water forms (up to) two hydrogen bonds (per molecule) but HF forms only
one.
(iv) NO2 ---> NO + O ( and the steps continue to form photochemical smog) [0.5]
- Fuel- The tip of the match stick is highly inflammable in nature when exposed
to heat and it acts as a fuel. [0.5]
- When the heat generated due to the friction, and fuel meet in the presence of
oxygen, we get fire [0.5]
(ii) N2O5 is more acidic as it gives a strong nitric acid when reacted with water
Q.57 (i) Orthophosphoric acid (H3PO4) is a strong oxidizing agent and it can't reduce 2
AgNO3.
(ii) Platinum has very high ionization energy and is one of the inert metals, hence
it does not react with moisture or air.
Q.58 - The precipitates of AgCl and AgBr dissolve in ammonia because they react with 2
it to form soluble complex salt containing Ag(NH3)2+ (aq.) [1]
Q.59 (i) Cl2 (aq.) + 2Br- (aq.) ----> 2Cl- (aq.) + Br2 (aq.) 2
(ii) Cyclohexane forms a layer on the top of water. Cyclohexane layer will be
brown in colour due to bromine molecules.
- to purify water
(ii) The (health) benefit outweighs the risk. Once it has done its job, little of it
remains
Or
Or
Q.62 Pt is used as a catalyst in the preparation of SO3 by direct combination of SO2 and 1
O2 at 450°C. In the reaction Pt is used as catalyst which_______
Q.63 In which of the following oxometal anions does the metal NOT exhibit an 1
oxidation state equal to its group number?
A. CrO42-
B. MnO4-
C. Cr2O72-
D. MnO42-
Q.64 Manav poured some potassium chromate in a test tube for qualitative analysis. 1
The yellow solution of potassium chromate soon turned orange in colour. Manav
realised that this happened because the test tube was not clean and contained
a few drops of some liquid.
Which of the following were the liquid drops most likely to be?
i) It is a coinage metal.
ii) It does not react with HCl but reacts with Nitric acid.
A. Zinc
B. Iron
C. Copper
D. Chromium
Q.66 Which of the following characteristics make transition elements good catalysts? 1
A. only P
B. only Q
C. only Q and R
D. all - P, Q and R
A. Catalytic action
B. Formation of alloy
C. Coloured complex formation
D. Interstitial compound formation
R) It is used as a germicide.
A. Only P. R, and S
B. Only Q, R, and S
C. Only S and R
D. Only P and Q
Reaction 1 Reaction 2
L High High
M Low High
N Low Low
O High Low
Which of the given options gives the correct magnetic properties of the given
Q.72 1
ions?
La = 57
Ce = 58
Yb = 70
Lu = 71]
Two statements are given below - one labelled Assertion (A) and the other
Q.73 1
labelled Reason (R).
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true.
Two statements are given below - one labelled Assertion (A) and the other
Q.74 1
labelled Reason (R).
Assertion (A): The atomic density of copper is less than that of chromium.
Reason (R): The atomic mass of copper is more than that of chromium.
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
X Y Z
-1.18 V -0.91V -0.44V
Which metal out of X, Y, and Z will be the most stable in the M2+ state? Give
reason.
Q.76 The preparation of potassium dichromate is a stepwise process, as shown below. 2
Step I - 4FeCr2O4 + 16NaOH + 7O2 ---> 8Na2CrO4 + 2Fe2O3 + 8H2O
Step II - 2Na2CrO4 + H2SO4 ---> Na2Cr2O7 + Na2SO4 + H2O
Step III - Na2Cr2O7 + 2KCl ---> K2Cr2O7 + 2NaCl
(a) What process should be used to remove impurities from sodium chromate
solution, after step I?
(b) What makes the reaction in step III possible?
Q.77 Why is mercury liquid at room temperature even though it is a metal? Give 2
reasons.
Q.78 A bottle contains compound 'A', which is the ammonical solution of nitrate salt 3
of a transition element. A chemical compound 'B', containing carbonyl functional
group is taken in a test tube. When compound 'A' is added in test tube containing
compound ' 'B' in basic medium. the wall of test tube B developes a shiny coating
on it. Based on this information, answer the following questions;
i) Write the formula and name of the compound present in bottle A.
ii) Which carbonyl compound in test tube B gives a silver mirror formation on
heating with compound A.
iii) Write a general chemical reaction taking place between chemical A and B.
The melting points of three elements J, K, and L were recorded. These three
Q.79 2
elements are from 1st, 2nd, and 3rd transition series (not necessarily in the order).
All of them have half-filled d orbital.
The melting point of J is more than K and melting point of K is more than L.
b) Give a reason for your choice of tensile strength and colour in aq. solution.
Complete the table given below:
Q.81 2
The ionic radii of certain elements of the 3rd transition series are tabulated
Q.82 2
below:
X+3 87 pm
Y+3 106 pm
Z+3 95 pm
Complete the table with respect to the samples given above with the given
information:
Sample I Sample II
Melting point
Chemical reactivity
Substance D is used for the bleaching of wool, cotton, silk and other textile fibres
Q.84 2
and for the decolourisation of oils. It is dark purple in colour and is almost
insoluble in water. The shape of the molecule is tetrahedral.
c) What is the bond angle of the central metal atom with the other atoms?
Look at the image given below and answer the questions that follow:
Q.85 2
a) State the valency of element D and the formula of its oxide in terms of ‘D’.
Q.63 D. MnO42- 1
Q.65 D. Chromium 1
Q.70 A. 109.5° 1
Q.71 B. M 1
Q.72 B. Both La+3 and Lu+3 are repelled by the applied magnetic field. 1
Q.73 B. Both (A) and (R) are correct and (R) is not the correct explanation of (A) 1
M2+/M = -1.18 V
which is the least reduction potential among the three metals. It suggests metal
X will undergo the reduction process very slowly hence it will show more stability
at X2+state or M2+state. [1]
Q.76 (a) Filtration 2
Q.78 i) 3
ii) Compound present in test tube B containing Aldehyde functional group gives
silver mirror formation.
Q.79 Element J is expected to valence electrons in the 5f orbitals. The melting point of 2
the element J is the highest among the three. So, it is expected to belong to the
3rd transition series with the valence electrons in 5f orbitals.
[1 marks for correctly identifying the element + 1 mark for the correct reason]
Q.80 a) 5
X 5s2,4d10 Low No
X>Z>Y
b) The overall decrease in atomic and ionic radii from lanthanum to lutetium (the
lanthanoid contraction) is a unique feature in the chemistry of the lanthanoids.
This is called 'Lanthanoid contraction.'
Q.83 Sample I Sample II 2
Q.84 a) The central atom in this compound is Mn+2 and the compound is D is KMnO4. 2
c) The bond angle of the central metal atom with the other atoms is 109° [0.5]
Q.85 a) The process seen here is alloying. The process of formation of homogeneous 2
solid solutions in which the atoms of one metal are distributed randomly among
the atoms of the other is called alloying. [1]
The element that shows deviation in the trend for the second ionisation energy
Q.87 2
is Manganese.
The element that shows deviation in the trend for the third ionisation energy is
Iron. [0.5+0.5]
The deviation occurs because Mn2+ ion and Fe3+ have 3d5 configuration which is
more stable than the configuration of Cr2+ and Mn3+ ions. [1]
Q.88 (a) It is evident from the crystal field splitting that the configuration of M changes 3
from d4 to t2g3 and eg1. (1)
Since the half-filled t2g3 level is more stable, the M2+ ion will furnish one electron
and will act as a reducing agent. (1)
(b) Metal ion M has n=4 and d4 configuration. Its electronic configuration will be
[Ar]4s03d4.
Compound A is Na2CrO4
Compound B is Na2Cr2O7
Compound C is K2Cr2O7
A. AgCl
B. AgNO3
C. BaSO4
D. BaCl2
Q.91 How many ions will be produced by the complex compound [Cr(en)3]Cl3 when it 1
is dissolved in water?
A. 2
B. 4
C. 7
D. 10
Q.92 In the complex compound Fe4[Fe(CN)6]3 oxidation states of counter ion Fe and 1
central metal ion Fe respectively are;
A. II, III
B. III, II
C. IV, III
D. II, II
A. II
B. III
C. 0
D. I
A. Δ0 = P
B. Δ0 < P
C. Δ0 > P
D. Δ0 ≥ P
A. Co-ordination isomerism
B. Linkage isomerism
C. Geometrical isomerism
D. Optical isomerism
Q.96 As per the Crystal field theory, which of the following is correct about the 1
repulsion between ligands and dxy, dyz, dzx orbitals in tetrahedral complexes?
A. [MnCl6]-3
B. [Ni(CN)4]-2
C. [Fe(CN)6]-4
D. [CuCl4]-2
Q.98 In an experiment Test Tube 'A' contains FeSO4(NH4)2SO4.6H2O solution and test 2
tube 'B' contains K3[Fe(C2O4)3] solution. On adding few drops of KSCN in the two
test tubes, solution of one of the test tubes turns into red.
i) Identify which out of two solutions in the test tubes 'A' or 'B' turns into red?
ii) Give reason why does one solution give red colour precipitate with KSCN but
other solution does not show any change.
Q.100 There are two samples solutions of complex compounds kept in two test tubes, 2
A and B. Test tube 'A' contains the solution of [Co(NH3)3Cl3 ] complex, and test
tube 'B' contains the solution of complex [CoCl2(en)2]+.
If plane polarised light is allowed to pass through these solutions, which sample
out of A and B can rotate plane polarised light and why?
If βn for the above reaction is 2.1x1013, find out the over all dissociation constant
of the complex.
1. Predict the denticity and charge on ligands A & B in the given complex.
2. Draw the structure of two geometrical isomers of the complex and name
them.
Q.106 Coordination compounds are of great importance in medicinal chemistry. 1
Explain how EDTA complex of calcium is useful in saving lives from hazardous
lead metal?
Q.108 Extraction of Silver from its ore Ag2S involves several steps. In one of the steps, 3
NaCN is added to the solution.
i) Explain the reason why NaCN is added to the solution?
ii)Why Zn metal is used to recover the Ag metal?
Explain with the help of chemical reactions.
Answer the following questions to describe the bonding in the metal carbonyl.
ii) What type of interaction between metal and CO ligands creates a synergic
effect?
iii) How is Δ0 value affected by the interaction of CO ligands and metal ion in
metal carbonyl?
Q.110 (i) Give a reason why all salts of sodium and potassium are white in colour. 3
(ii) What will be the formula of Cr+3 complex with H2O and Cl- as ligands if its
molar conductivity is similar to salt with the formula AB2. [A is the metal and B
is the non-metal].
Q.111 (a) Mrs.Dey is a goldsmith. She got an order to make a silver bangle. Write down 4
the equations of the reaction that is most likely to be carried out by her workers
in her workshop to extract the required silver from its sulphide ore.
(b) Write the distribution of the electrons in the central metal ion of the
coodination complex formed after extraction of silver. Justify your answer.
Q.112 In an unknown complex [M(X)4], the oxidation state of central metal is zero i.e.M 2
(0). If in an experiment metal M is found to be Ni then predict whether the
ligand X in the formula is CO or CN to give a stable complex. Justify your answer
and predict the shape of the molecule.
Q.113 When AgNO3 solution is added into the solution of a co-ordination compound 2
PdCl2.4NH3, it produces 2 moles of AgCl precipitate.
- counter ions
Q.114 (i) A co-ordination compound [Co(x)6]3- shows d2sp3 hybridisation. Identify the 3
nature of ligand x as weak or strong.
(ii) Explain how does the presence of ligand x affect crystal field splitting
energy Δ0 and pairing energy P.
(atomic number of Cobalt is 27)
Q.90 D. BaCl2 1
Q.91 B. 4 1
Q.92 B. III, II 1
Q.93 B. III 1
Q.94 B. Δ0 < P 1
Q.97 C. [Fe(CN)6]-4 1
Q.98 i) Solution of FeSO4(NH4)2SO4.6H2O in Test Tube 'A' will turn into red. [1] 2
ii) FeSO4(NH4)2SO4.6H2O solution in Test Tube 'A' is a double salt and it ionises
fully in aqueous solution.The Fe2+ions in solution reacts with KSCN and give red
colour due to formation of FeSCN2+ complex. [0.5]
- four CN ligands are strong ligands which allow pairing of electrons in 3d-
orbitals and donate pair of electrons in next empty d s p2 orbitals. [1]
- Presence of 4 unpaired e-in 'd' orbital makes it para magnetic .Thus complex
is weakly attracted towards magnetic field. [1]
Q.100 - Sample solution [CoCl2(en)2] in test tube B can rotate plane polarised 2
light. (1)
- The spatial arrangement of two didentate ligands ethylene diamine and two Cl
monodentate ligands around the metal ion is such that it makes the molecule
unsymmetrical. such molecules are optically active i.e.they can rotate plane
polarised light. (1)
D.C. = 1/2.1x1013
Thus
D.C. = 4.7x10-14
since two mole AgCl is produced hence 2 chloro groups are present as primary
valencies.
In complex [Cr(H2O)6]Cl3 six aqua ligands make direct bond with Cr metal ion
thus complex is octahedral. (1)
In any complex the sum of charges on ligands and counter ions shows oxidation
state of metal ion which is +3 in Co.
[Co(a)4(b)2]Br
Since both a and b ligands are monodentate it is clear b has charge-1 and charge
on a is 0
x = +3
Q.104 - Since complex has 3 didentate ligands there must be 6 donor atoms present 3
around the central metal M (1)
Six donor atoms around the metal ion suggest complex is octahedral. (1)
Q.105 1. Since oxidation state of metal ion M is +3, therefore the charge on one of the 4
ligands is 1 and the other will have charge =0
while writing the formula the neutral ligand is written before anionic ligand.
Hence
A monodentate 0
B monodentate -1
2. Meridional isomer(mer)
Q.106 - EDTA makes Lead substituted complex with poisonous lead in the body which 1
can be easily excreted by the body. (1)
(fig. is optional)
(ii) The d orbital splitting here is more influenced by the charge on metal ion.
For the similar metal ion complexes, the higher is the charge on metal ion more
is the splitting energyΔ0 . Similarly lower is the charge on metal ion less is crystal
field splitting. (1)
ii)To obtain metal Ag in precipitate form Zn metal is added into the solution
which helps in the displacement of Ag from the complex. (1)
Na[Ag(CN)2] + Zn ------>
Q.109 i) The donation of a lone pair of electrons from ligand CO to metal ion forms σ 5
bond.
ii) In metal carbonyl the CO to Metal bond C → M is a sigma (σ) bond. There is
also an overlapping of electrons from filled metal d orbitals into empty
antibonding orbital of CO.This results into formation of a π bond and called back
bonding. [1]
- The M → C bond strengthens the bond between CO and the metal and this
type of bonding creates a synergic effect. [1]
(iii) Δ0 value that is crystal field splitting energy increases in metal carbonyl. [1]
Q.110 (i) The colour of a salt arises due to two main factors: 3
1. Influence of ligands present in a salt.
2. Presence of incomplete d-subshells.
- Both potassium and sodium lack incomplete d-orbitals. So, when light falls on
such complexes no excitation of electrons occurs to higher energy levels to
absorb or emit light of a certain wavelength. Hence, such salts are white in
colour.
[Give 0.5 mark each for points 1 and 2, and 1 mark for the explanation]
(ii) A complex having molar conductivity similar to AB2 should release 3 ions in
the solution. Thus, the probable formula of the complex will be:
Q.111 (a) The ore of silver is Silver sulphide(Ag2S).The reactions that are most likely to 4
be carried out in the workshop by Mrs. Dey are:
[Give 1 mark for each correct equation. No marks to be awarded if the equations
are not balanced.]
(b) Zinc forms a tetrahedral complex in this case. As Zn+2 has 10 electrons in its
d-shell so pairing of electrons occur and the distribution of the electrons is e4t6 .
[Give 1 for correct distribution of electrons and 1 mark for the correct reason.]
hence 4 CO ligands will occupy four sp3 hybrid orbitals thus complex is
tetrahedral. (1)
Q.113 - In any complex compound co-ordination entity is that part which contains 2
ligands and metal ion together in a sphere. Thus
- Counter ions are ionisable part which takes part in reaction hence
- The number of attacking sites used by ligands around the metal ion represent
coordination number
(ii)
- pairing of electrons in lower 'd' i.e. t2g shows pairing energy is lower
than Δ0 i.e. Δ0 > P . (0.5)
Q.115 Three graphs P, Q and R have been drawn to represent the relative rates of 1
hydrolysis reactions for primary, secondary, and tertiary haloalkanes.
Which of the following correctly identifies the graphs that represent SN1 and
SN2 reactions?
W graph P graph Q
X graph Q graph P
Y graph R graph Q
Z graph Q graph R
A. W
B. X
C. Y
D. Z
Which of them would be the most easily undergo SN1 and SN2 reactions?
P tert-iodobutane iodobutane
Q tert-bromobutane bromobutane
R iodobutane tert-iodobutane
S bromobutane tert-bromobutane
A. P
B. Q
C. R
D. S
Q.117 The table below shows some of the features of SN1 and SN2 reaction 1
mechanisms.
Which of the rows shows an INCORRECT feature for at least one of the
mechanisms?
A. A
B. B
C. C
D. D
Q.118 Which of the following will be the major product formed in the reaction below? 1
A. 3-iodopentane
B. 2-iodo-2-methylpropane
C. 1,3-diiodopropane
D. 2-iodobutane
Q.120 The image below shows the ball and stick model of 4 different compounds. 1
A. 1
B. 2
C. 3
D. 4
Q.121 Which of the following compounds will be hydrolysed most rapidly under similar 1
reaction conditions?
A. 1-chloropropane
B. 1-chlorobutane
C. 2-chloro-2-methylpropane
D. 2-chlorobutane
As per the Fittig reaction, when 2 moles of chlorobenzene reacts with metals
such as sodium in the presence of dry ether, it gives diphenyl.
A. 1
B. 2
C. 3
D. 4
A. 1
B. 2
C. 3
D. 4
Q.124 The image below shows different stages for a SN1 reaction. 2
(ii) What will be the rate equation for the reaction (CH3)3CBr with I- ? Justify.
Q.126 The table below gives data about four different gaseous compounds. 3
P CCl3F 45 24
Q.127 For each of the following combinations of reagents and conditions, suggest 3
whether substitution or elimination will predominate. Justify your answer.
(p) heating CH3CH2CH2Br with aqueous NaOH
(q) heating (CH3)3CBr with NaOH in ethanol
(r) heating (CH3)2CHBr with (CH3)3CO-K+
Q.131 Do any of the possible structures of C5H11Cl show stereoisomerism? If no, then 2
explain why. If yes, draw the 3D diagram of the enantiomers.
(1) heating the reactants for around 50 minutes in the apparatus shown in figure
1
(2) distilling the reaction mixture to obtain the product 1-bromobutane in the
apparatus shown in figure 2
(a) Explain why the reactants are heated for 50 minutes in stage 1.
(b) What is the function of condensor in stage 1 and in stage 2? How does it help
the reaction?
Q.134 The image below shows two competing routes or reactions when a haloalkane 4
reacts with water in the presence of alcohol. The major products under each of
the routes are shown.
Q.135 Haloalkanes are important compound which are produced at scale for industrial 2
purpose. To increase the efficiency and reduce the cost of production, scientists
use different combinations of reactants and reaction conditions.
Q.136 Study the reaction below and answer the questions that follow: 3
CH3Cl + NaI CH3I + NaCl
(i) How can we increase the rate of the forward reaction?
(ii) If methyl fluoride is to be prepared by the above process, state the
reactants?
(iii) Arrange methyl iodide, methyl fluoride and methyl chloride in the
decreasing order of their dipole moment.
Q.137 An organic compound with the formula C6H5Br reacts with CuCN to form 3
compound ‘P’ and CuBr in presence of pyridine at 475 K. Compound P on
reaction with dil. HCl forms compound ‘Q’ which reacts with methyl alcohol
produces a sweet smelling compound ‘R’.
Q.138 Give a reason why vinyl halides generally do not undergo nucleophilic 1
substitution reactions.
Q.139 To prepare a Grignard reagent, Udita mixes magnesium metal in dry ether with 1
the compound shown below.
CH3 - CHOH - CH2 - CH2Br
Will she obtain the Grignard reagent? Justify your answer.
Q.140 The table below shows the effect of aqueous silver nitrate on bromine 3
containing compounds at room temperature.
Q.115 D. Z 1
Q.116 A. P 1
Q.117 C. C 1
Q.119 D. 2-iodobutane 1
Q.120 A. 1 1
Q.121 C. 2-chloro-2-methylpropane 1
Q.122 C. 3 1
Q.123 C. 3 1
- the carbocation is very unstable and reactive so the second step will be fast
[0.5]
- because in SN2 reaction the incoming nucleophile (I-) interacts with the
substrate (bromopropane) causing the C - Br bond to break and a new C - I bond
to form. These two processes occur simultaneously in a single step without the
formation of any intermediate. The rate of reaction is determined by the
concentrations of both the reactants. [1]
Q.126 (i) CCl2F2 decomposes under UV light to give free radical chlorine which reacts 3
with ozone and destroys the ozone layer.
(b) Elimination; In a less polar solvent like alcohol, elimination predominates for
tertiary haloalkanes with OH ions [1]
(c) Elimination; elimination predominates due to steric effect as the base used
is bulky group [1]
[1]
[1]
(ii)2-bromobutane [1]
Q.131 - Yes; 2
structure of enantiomers:
Q.132 (a) This substitution reaction is very slow in nature and hence takes a long time. 3
- In stage 1, it condenses vapours and returns liquid to the flask thus allowing
the reaction mixture to be heated at the boiling point without any loss of the
reactant.
Q.133 (i) 3
- Due to the steric effect of the bromine group, substitution at the ortho position
is hindered and preferably occurs at the para position.
Q.134 (i) - For reaction 1, water can behave as a nucleophile and donate a lone pair 4
(from oxygen) and attack (positive) carbon (originally attached to Cl)
carbocation [1]
Reasons:
Q.135 - C2H4 2
Q.136 (i) The rate of the reaction can be improved by precipitating NaCl in dry acetone. 3
(ii) The reactants needed to prepare methyl fluoride is methyl chloride or methyl
bromide and any metallic fluoride such as AgF, Hg2F2 , CoF2 or SbF3.
[Give 1 mark for each correct answer. Marks should be granted if the answer is
written correctly in own words.]
Q.137 The chemical reactions showing the conversions are: 3
Formation of P:
Formation of Q:
Formation of R:
Q.140 (i) The C-Br bond in 1-bromobutane is covalent in nature, therefore it does not 3
produce Br ions immediately.
(ii) Bromine is more electronegative than carbon, so the C-Br bond is polar
[0.5]
- The partial positive charge on carbon attracts nucleophiles with their lone pairs
of electrons. [0.5]
- Water molecules from silver nitrate attack the partial positive carbon, and a
substitution reaction takes place, releasing bromine ions after some time. [1]
Q.141 The pKa of phenol is lower than that of ____________ which is a _______ acid 1
than phenol.
A. ethanol, weaker
B. o-cresol, stronger
C. m-nitrophenol, weaker
D. p-nitrophenol, stronger
Q.143 Anupam tabulated the time required for the reaction of different halogen 1
halides with diethyl ether as follows:
Halogen halide HW HX HY
Q.144 The table below shows the number of hyperconjugation structures of three 1
carbocations:
P 3
Q 9
R 6
A. R<Q<P
B. Q< R< P
C. Q<P<R
D. P < R <Q
T: CH3CH2CH2CH2OH
U: CH3CH2CH=CH2OH
V: CH3OCH3
A. S
B. T
C. U
D. V
Two statements are given below - one labelled Assertion (A) and the other
Q.146 1
labelled Reason (R).
Assertion (A): The carbon–oxygen bond length in phenol is slightly less than that
in methanol.
Reason (R): The hybridised state of carbon to which oxygen is attached sp3 in
phenol.
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
Q.147 Two statements are given below - one labelled Assertion (A) and the other 1
labelled Reason (R).
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
A. only P
B. only P or Q
C. only Q or R
D. any of P, Q or R
-
A. CCl3
B. :CCl2
+
C. CHCl2
+
D. CHO
Q.151 Neha knows that aldehydes react with a Grignard reagent to give a secondary 3
alcohol as the final product. She carried out the reaction sequence shown below
to prepare 2,5-dihydroxyheptane.
Q.152 Phenol reacts with dil. HNO3 at low temperature. The products are separated 3
into two beakers. Zainab and Christine recorded the boiling of the compounds
as given in the tables below:
Christine's readings:
1 489 K
2 387 K
Zainab's readings:
1 387 K
2 489 K
-Compound Q does not form any silver mirror with Tollen's reagent.
(b) Give the IUPAC names of the compounds formed from Q and R.
(c) Write the reaction showing the formation of the primary and tertiary
alcohols.
Q.154 Complete the table by comparing between Benzyl alcohol and Phenol: 2
Benzyl Phenol
alcohol
Q.155 Susmita tabulated the graph given below showing the variation of bond angles 4
of three compounds.
The compounds taken by Susmita are ethanol, phenol, and diethyl ether.
(b) Arrange the compounds in the decreasing order of C-O bond length.
Compound D E F
percentage of s-character
Q.158 Write the structure of all the products formed when n-propyl alcohol is heated 3
with ethyl alcohol in the presence of concentrated sulphuric acid.
Q.145 C. U 1
Q.147 A. Both (A) and (R) are correct and (R) is the correct explanation of (A) 1
Q.148 A. only P 1
Q.149 B. :CCl2 1
- In the third step, deprotonation occurs to give the alcohols shown in (a) as the
major and minor products
Q.151 (a) The Grignard reagent reacts with the alcohol group on the molecule Y to 3
form the hydrocarbon.
Tertiary alcohol
(d) The first step of the reaction is the nucleophilic addition of Grignard reagent
to the carbonyl group to form an adduct.
C-O-H bond angle is the compounds with of the partial double bond
1090 because sp3 hybridisation have character on account of the
a bond angle of 109° unshared electron pair of
oxygen with the benzene
ring
F: diethyl ether
(c)
Compound D E F
Q.157 This is not a good method for the preparation of n-propyl ethyl ether. 2
The reaction will produce a mixture of three different ethers which would be
difficult to separate.
Q.160 3
(i)
(ii)
(ii) benzaldehyde
(a) Give a possible explanation why sodium benzoate and methanol are not
formed in the crossed Cannizzaro reaction.
- The aldehyde that undergoes nucleophilic attack by OH- is converted to the sodium salt
of the acid and the other aldehyde to the alcohol.
(b)
- Yes [0.5]
Q.162 5
Since it gives the iodoform reaction, it must have a methyl group linked to the
carbonyl carbon atom and is, therefore, a methyl ketone.
- using the molecular formula together with the points above, we arrive at the
structure of the compound
Q.163 The reaction of an arene diazonium chloride with aniline in an acidic medium 1
gives a coloured compound.
Q.164 Which of the following is TRUE about the solubility of Ethylamine and Aniline? 1
Q.165 During an activity session, the teacher kept some pieces of papers in a box in 1
which the names of chemicals were written. The teacher then asked 4 groups
of students to select the appropriate pieces of paper with names of chemicals
used to prepare para nitro aniline. The 4 groups have selected pieces of paper
as follows;
A. Group1 and 4
B. Group 3 and 4
C. Group3
D. Group 1
Amine F 30
Amine G 49
Amine H 100
Which of the following statements is most likely to be TRUE about these three
amines?
Q.167 Two statements are given below - one labelled Assertion (A) and the other 1
labelled Reason (R).
Q.168 Aniline on heating with chloroform and alcoholic KOH gives a foul-smelling 1
product.
Making which of the following changes in the reaction would still produce a foul-
smelling product?
A. only P
B. only R
C. only Q and R
D. only P and R
A. benzonitrile
B. aniline
C. nitrobenzene
D. benzylcyanide
Which of the options correctly identifies the amount of ammonia and alkyl
Q.170 1
halide used in the reaction and the type of amine obtained?
A. L
B. M
C. N
D. O
The graphs below show the solubility of a primary, a secondary and a tertiary
Q.171 1
aliphatic amine I, J, and K in water, at the same temperature. The number of
carbon atoms in each of the compounds is three. Amine I is the tertiary amine,
amine J is the primary amine, and amine K is the secondary amine.
A. P
B. Q
C. R
Two statements are given below - one labelled Assertion (A) and the other
Q.172 1
labelled Reason (R).
Reason (R): In acidic medium aniline gets protonated forming anilinium ion.
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
Two statements are given below - one labelled Assertion (A) and the other
Q.173 1
labelled Reason (R).
Reason (R): The cyano group can directly be introduced in a benzene ring by
substitution.
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
Two statements are given below - one labelled Assertion (A) and the other
Q.174 1
labelled Reason (R).
Assertion (A): Propyl amine on reaction with nitrous acid forms aliphatic
diazonium salts.
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
Q.176 Two isomers, n- C4H9NH2 and (C2H5)2NH have molar mass of 73 each. 1
Q.177 Aryl diazonium salts undergo reductive removal of the diazonium group in 1
presence of weak acids.
A. Chlorobenzene
B. Phenol
C. Benzene cyanide
D. Benzene
Q.178 Benzene sulphonyl chloride is a chemical which can be used to identify the class 1
of an Amine. When an amine 'A' reacts with benzene sulphonyl chloride it gives
precipitate of sulphonamides which is soluble in alkali. The amine A is;
A. N-Ethylethanamine
B. N,N-Diethylethanamine
C. Ethanamine
D. N-Methylbenzenamine
Q.179 2-Methyl butanamide on reacting with Br2 in alkaline medium gives an amine. 1
Which of the following is a correct characteristic of that amine?
A. It is optically active.
B. It is a secondary amine.
C. It can form a stable diazonium salt.
D. It has one carbon atom more than the amide.
Q.182 Which out of H-NH2 and CH3-NH2 has higher pKb value? Illustrate the 3
ionisation of these compounds in aqueous medium and write their
Kb expression to justify your answer.
Q.183 Two beakers 'A' and 'B' contain aqueous solutions of methyl amine. It is 4
observed that beaker A contains more OH- than beaker 'B'
Prove which of the two solutions will have higher pKb value and why?
Q.184 There are 5 reagent bottles containing NaNO2, HCl, Phenol, Aniline and NaOH 3
separately in them. The teacher asked Amit to make an orange dye using
suitable chemicals out of the five reagents given.
(a)Write the chemical equations and the conditions for the steps involved in the
preparation of the orange dye.
(b) Name the type of reaction of the step in which phenol reacts.
Q.185 (a) Why are quarternary ammonium salts used in detergents? Explain it by 3
giving one example.
(b) Write the chemical reaction involved in the Ammonolysis process of
preparation of quarternary ammonium salt.
Q.186 During an activity period, the teacher asked the students to write the chemical 3
reactions involved in the conversion of compound Cl-(CH2)4-Cl into hexane-1,6
diamine. She also suggested students to use chemicals such as reducing agents,
alcohol, cyano compounds etc as per the requirements.
She then asked them to report their findings by answering the following:
i) Write the chemical reaction taking place in first step of the conversion.
ii) Identify the type of reaction. Justify.
iii) Show the chemical reaction for the formation of the final product.
Q.188 Primary and secondary amines undergo acylation reaction in the presence of a 3
stronger base than the amine.
(a) What would happen if a stronger base is not used for the acylation reaction?
(b) Can we use anhydrous AlCl3 in place of a strong base? Justify your answer by
writing the reaction.
Q.189 (a) When benzene diazonium chloride is treated with fluoroboric acid it gives a 5
compound 'X'.
Identify compound X.
(b) When compound 'X' is heated alone or with NaNO2 in the presence of Cu it
releases N2 gas.
What are the other two products produced when compound 'X' is:
i) heated alone?
ii) heated with NaNO2?
Write the chemical equations involved in each of the reactions.
Anusrita was measuring the pKb of of two compounds A and B. She recorded
Q.190 3
her observations in the following table:
A B
Q.193 (a) Identify the type of amines M,N, and O in the flowchart below: 3
(id Write balanced equations showing the formation of the yellow and orange
dyes.
Q.195 Of the two compounds P and Q given below, which one is more likely to be 2
acidic in nature? Justify your answer.
Q.196 While studying about diazotisation of amines and their reactions, students 2
carried out the following two processes P and Q in the laboratory to prepare
orange-coloured dye.
P) aniline + dilute HCl + NaNO2 + ice _____30 minutes __ > X _______+ phenol_____>
Q) aniline + dilute HCl + NaNO2 _____30 minutes ____
> X _______+ phenol_____>
Which of the two processes is likely to produce the orange-coloured dye in
higher yield? Justify your answer.
Q.197 Krishna took three amines U, V, and W. The three amines were added to 5
Hinsberg’s reagent. The products were added to aq. NaOH and the observations
were tabulated as follows:
(a) What is Hinsberg’s reagent? Name another reagent that can replace this one.
(c) What does the solubility of the products formed in aq. alkali imply?
(d) Which of the following amines may be prepared by the Gabriel phthalimide
process? Give a reason.
With the same input of the reactant the output in method I is 25cc of
chlorobenzene and in method II 30cc of chlorobenzene is produced.
Q.169 A. benzonitrile 1
Q.170 C. N 1
Q.171 D. S 1
Q.172 A. Both (A) and (R) are correct and (R) is the correct explanation of (A) 1
Q.177 D. Benzene 1
Q.178 C. Ethanamine 1
Q.181 - In C6H5-NH2, the unshared pair of electrons on nitrogen is conjugated with the 2
benzene ring making it less available for protonation than in ammonia. [1]
The CH3 group is an electron releasing group. This makes the unshared pair of
electrons on N more available and a stronger proton acceptor than ammonia.
[1]
We know -
pKb = - log Kb
Methanamine ionises
_______
CH3-NH2 + H2O >CH3NH3++ OH-
Q.183 Presence of more OH- ions shows solution 'A' is more basic. 4
Thus we can say pKb value of solution 'B' is higher because it has less
concentration of OH-. [1]
Q.184 (a) 3
(i) 0.5 marks each for writing the formula of aniline and benzenediazonium
chloride and 0.5 marks for mentioning the temperature:
(ii)0.5 marks each for writing the formula of phenol and p-hdroxyazobenzene
Q.185 Quarternary ammonium salts, which have one of the R= long hydrocarbon 3
chain, are used in detergents because they can serve as surfactants.
ex .
(1 mark each for the explanation and the example)
Preparation :
______
R-X + NH3 > RNH2
(A)
Compound A is Alkanamine.(RNH2)
RNH2 + 3R-X ____> R4N+X (detergent) (1)
i) At first chloro compound will be converted into cyano compound.So first step
is-
______
Cl-(CH2)-Cl + KCN(alc.) > NC-(CH2)4-CN (1)
H2N-CH2-(CH2)4-CH2-NH2 (1)
Q.188 (a) 3
- In the reaction, the corresponding amide is formed with the release of acid
HCl. This acid is neutralised by the stronger base present in the reaction thus
equilibrium will shift in forward direction [1]
- If a stronger base is not used then the HCl formed in the reaction will be
neutralised by aniline itself and this will make the reaction to stop after a point.
[1]
(b) No, we cannot use anhydrous AlCl3 in place of a base because AlCl3 is a Lewis
acid and amines are Lewis bases. They both will react to give the corresponding
salt and not amide.
(b) (i) When compound X is heated alone it gives fluorobenzene and boron
trifluoride with the release of N2 gas.
[Give 0.5 marks each for mentioning the two products and 1 mark for the correct
equation]
(b) (ii)
[Give 0.5 marks each for mentioning the two products and 1 mark for the correct
equation]
(c) Quaternary amines have greater bond angle than tertiary amines.
Quaternary amines are sp3 hybridized, have a tetrahedral shape, and have a
bond angle of 109.5o. Due to the presence of unshared pair of electrons, the
bond angle is less than 109.5° in the case of triethylamine.
[1 mark for the correct bond angle and 1 mark for the reason.]
Q.192 (a) 4-methylaniline < 3-methylaninline < aniline < 2-methylaniline. [1] 3
(b) The methyl group is an electron-releasing group. Its effect is more at the p-
position than at the meta position. So, 4-methylaniline is more basic than 3-
methylaniline. The basic nature of 2-methyl aniline is expected to be more than
aniline because of the +I-effect of the -CH3 group. But it is less than aniline due
to the steric effect of the -CH3 and the -NH2 group in close proximity. The basic
nature of 3-methyl aniline will be more than aniline because of the +I-effect of
the -CH3 group. The more basic the nature, the lower the pKb value.
(b) C6H5NH2 + NaNO2 +2HCl -------> C6H5N2+Cl- (compound X)+ NaCl + 2H2O
[1]
(c) Due to its instability, the benzene diazonium chloride salt is not generally
stored and is used immediately after its preparation. [1]
(d)
C6H5N2+Cl- + C6H5NH2
C6H5N2+Cl- + C6H5OH
Q.196 The orange-coloured dye will be produced in larger amounts by process P. [1] 2
Q.197 (a) Benzene sulphonyl chloride (C6H5SO2Cl), which is also known as Hinsberg’s 5
reagent. Benzene sulphonyl chloride is replaced by p-toluene sulphonyl
chloride. [0.5+0.5]
(b) Amine V and W have the structural formula of R-NH-R. [0.5+0.5]
(c) The hydrogen attached to nitrogen in the product formed after the amine U
reacts with Heisenberg’s reagent is strongly acidic due to the presence of a
strong electron-withdrawing sulphonyl group. Hence, it is soluble in aq.NaOH.
Amine V and W do not contain any hydrogen atom attached to the nitrogen
atom in the product formed are not acidic and hence insoluble in aq.NaOH.
(d) Amine U is soluble in aq. NaOH. So, it is a primary amine. Gabriel synthesis is
used for the preparation of primary amines. [0.5+0.5]
Q.200 When a mixture of sodium nitrite with hydrochloric acid at 40°C is added to 2
aniline, benzene diazonium chloride is formed. This compound decomposes at
high temperatures. [1]
Since Prapti leaves this reaction mixture beside an open window on a hot and
sunny day the temperature will be above 10°C and the diazonium compound
decomposes to phenol. [1]
Method I Method II
[0.5+0.5]
Q.202 (R)3N is more basic as in this N has a lone pair of electron which it can 2
donate.Thus it can acts as Lewis base. [1mark]
On the other hand in (R)4N+Cl- the lone pair of N is already protonated. Hence
it is less basic. [1]
A. Compound A is neutral.
B. Compound A is basic in nature.
C. Compound A is acidic in nature.
D. Compound A is ammonium salt.
A. Both Assertion (A) and Reason (R) are the true and Reason (R) is a correct
explanation of Assertion (A).
B. Both Assertion (A) and Reason (R) are the true but Reason (R) is not a
correct explanation of Assertion (A).
C. Assertion (A) is true and Reason (R) is false.
D. Assertion (A) is false and Reason (R) is true.
Assertion (A): Sucrose and Fructose can not give positive Tollen's test
Q.205 1
Reason (R): Sucrose and Fructose do not contain an aldehyde group.
A. Both Assertion (A) and Reason (R) are the true and Reason (R) is a correct
explanation of Assertion (A).
B. Both Assertion (A) and Reason (R) are the true but Reason (R) is not a
correct explanation of Assertion (A).
C. Assertion (A) is false and Reason (R) is true.
D. Assertion (A) is true and Reason (R) is false.
(i) Amongst Lysine, Histidine and Serine, Lysine is the most basic in nature.
(iii) Adding acids such as lemon juice into meat protein does not denature the
primary structure yet tenderize meat.
A. i only
B. iii only
C. i and iii only
D. all- i, ii, and iii
Q.207 Given below are two statements labeled as Assertion (A) and Reason (R). 1
Reason (R): Amino acids can form zwitter ions. The ionic nature of the zwitter
ions gives amino acids relatively strong intermolecular forces of attraction.
Select the most appropriate answer from the options given below:
A. A
B. B
Q.210 Which of the following statements is/are correct proteins or enzymes when 1
they are subjected to physical changes as specified?
(i) The sequence of amino acids in the peptide changes in a protein when the
pH of its environment is changed.
(iii) Albumen, a globular protein found in egg whites, sets into an insoluble white
solid when the egg white is heated.
A. iii only
B. i and ii only
C. ii and iii only
D. all- i, ii, iii
Q.211 The following image shows the structure of DNA, with the letters indicating the 1
bases present.
A. Primary
B. Secondary
C. Tertiary
D. Quarternary
(i)
(ii)
The mixture of the amino acids* consisted of glycine, lysine and glutamic acid
at pH 7 (at which the amino acids are neither acidic nor alkaline). When an
electric field is applied to this mixture and left for a certain period of time, the
mixture separates as shown below.
Identify the amino acids that would be found in spots labelled D, E and F. Give
a reason to support your answer.
[Molecular formulae:
Q.214 The amino acid alanine, CH3CH(NH2)COOH, reacts with glycine, H2NCH2CO2H. 2
Show how this produces two dipeptides with different structures.
Q.215 How many possible sequences of tripeptides can be formed from the three 4
amino acids Gly, Ala, and Ser, if each tripeptides contains all three amino acids?
Also write down the name of all sequences of these tripeptides.
Q.216 Amino acids can act as buffers, stabilising the pH of a solution if excess acid or 2
alkali is added. Show this with the help of reactions of acids with a acid (H+) and
a base (OH-).
Q.217 Due to the formation of zwitter ions by amino acids, they show many of the 3
typical reactions of amines and carboxylic acids like esterification, and acylation
reactions.
(i)
(ii)
Q.218 The image below shows a small part of single strand of DNA. The DNA continues 4
bond at X and Y.
guanine
(i) Which of these two bases pairs with the guanine in first image when two
seperate strands of DNA form a double helix?
(ii) Explain how the base that you have selected in i, forms a base pair with
guanine.
Draw the structure of the organic products formed when alanine reacts with:
(ii) Na2CO3
(i) Is it possible to get the original amino acids from this structure? If yes, how?
(ii) What will be the structure of the amino acid B in the aqueous solution?
(i)Name the reagent used in step 3. What is the necessary condition for this
reaction to take place? Name the mechanism.
(ii) At room temperature, the amino acid X exists as a solid. Draw the structure
of the solid amino acid.
(iii) With reference to your answer to part (ii), explain why the melting point of
the amino acid X is higher than the melting point of CH3CH2CH(OH)COOH
Q.223 Peptides can be hydrolysed into individual amino acids, for example: 2
(i) How many water molecules would be required to hydrolyse a peptide made
from 'n' amino acid molecules?
Mr. Chatterjee was having pain in his joints. The shape of one his canines and
Q.224 4
some of his toes got deformed a bit. He visited the doctor. Along with the
medications he was asked to take ample amounts of milk, and eggs. He was also
asked to take cod liver oil capsules. The doctor asked Mr. Chatterjee to expose
himself to sufficient sunlight every day.
(a) What is the most probable disease that Mr. Chatterjee is suffering from?
(c) How can exposure to sunlight help in improving the health condition of Mr.
Chatterjee?
Q.225 (a) Amongst the following amino acids, which is the most basic in nature? Why? 3
Glycine H
Lysine H2N-(CH2)4
Serine HO - CH2
(b) How do acids such as lemon juice tenderise the meat while using it in a
marinade?
Q.208 D. D 1
Q.209 D. D 1
Q.211 A. Primary 1
Q.212 (i) 2
(ii)
Q.213 - At pH 7, glutamic acid carries an extra negative charge and moves towards the 3
positive electrode – it is responsible for spot D.
- At pH 7, lysine carries an extra positive charge, and hence moves towards the
negative electrode – it is responsible for spot F.
Q.217 3
(i)
(ii) For hydrogen bonding to happen, cytosin's top N–H forms hydrogen bonds
to lone pair on O of guanine [1]
Q.219 2
(i)
(ii)
(ii)
Q.221 2
(i)
Q.222 (i) 4
[ignore concentrated]
(ii)
(ii)
The change in pH leads to breaking of the hydrogen bond and salt bridges in the
protein molecules of milk. Thus the proteins in milk get denatured and the milk
curdles.
[Give 1 mark for each correct answer. Students may write the answer in their
own words.]
[Give 1 mark for each correct structure. Students may write the answer in their
own words.]
(b) Acidic ingredients in the marinade, like lemon juice, will tenderise meat by
denaturing or unwinding the long protein in the meat by breaking apart the
amino acids.
Q.227 Which of the following monomers will be best suited for preparing a polymer 1
used for manufacturing non-stick cookware?
A. ethene
B. acrylonitrile
C. tetrafluoroethene
D. terephthalic acid
Q.228 Two different polymers are made from the same monomer unit. Polymer 1 is 1
used to make flexible pipes while polymer 2 is used to make dustbins.
Choose the option which correctly matches each polymer to the reaction
condition which is appropriate for its preparation.
Polymer 1 Polymer 2
A. L
B. M
C. N
D. O
Q.229 Which of the options correctly identifies the characteristics of the polymer 1
formed from the monomer unit given below.
P √ √ √
R √ × √
S × √ √
A. P
B. Q
C. R
D. S
Q.230 Which of the following objects are generally made from polymers prepared by 1
the free radical mechanism of polymerisation?
A. Buckets
B. Conveyor belts
C. Non-stick utensils
D. Bristles for brushes
Q.231 Two statements are given below - one labelled Assertion (A) and the other 1
labelled Reason (R).
Reason (R): Condensation polymerisation may result in the loss of some simple
molecules such as water, alcohol, hydrogen chloride, etc.,
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
Q.232 Two statements are given below - one labelled Assertion (A) and the other 1
labelled Reason (R).
Assertion (A): The growth of the polymer chain during their synthesis is
dependent upon the availability of the monomers in the reaction mixture.
Reason (R): The rate of the reaction of the monomers depends only on the
temperature of the reaction mixture.
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
Q.233 Piyush stretched a rubber band and then released it. He saw the rubber revert 2
to its original shape. When he applied a bit more force the rubber band
snapped.
Give an explanation for both these observations.
Q.234 Give one example of the polymers G, H, and I from the flowchart given below: 3
Q.235 Read the passage and answer the questions that follow: 5
Plastic waste can accumulate in the ecosystem. It happens due to the
accumulation of marine litter, fragments or microparticles of plastics, and non-
biodegradable fishing nets, plastic products, etc. Ingestion of these wastes or
getting trapped in the waste causes the death of animals.
These plastics are made from polymers that are quite resistant to
environmental degradation processes and are thus responsible for the
accumulation of polymeric solid waste materials.
(a) Name the class of biodegradable polymers. What is the similarity of this
polymer with the biopolymers?
(b) Name a copolymer that is biodegradable and write an equation showing its
formation. State any two of its uses.
(c) State the advantage of the polymer described in (b) over the polymers seen
in the image.
Q.227 C. tetrafluoroethene 1
Q.228 C. N 1
Q.229 B. Q 1
Q.231 B. Both (A) and (R) are correct but (R) is not the correct explanation of (A) 1
Q.233 - Rubber is a polymer that has a few ‘crosslinks’ which help the polymer to 2
retract to its original position after a small force that is applied is released. [1]
- The polymer chains are held together by the weak intermolecular forces that
help in the stretching of rubber. But when stretched beyond a limit, these weak
forces break and the rubber band snaps. [1]
0.5 marks each for any two examples of each type of polymer:
Q.234 3
G: cellulose, starch or any other correct example of a natural polymer.
Q.235 (a) 5
- The similarity of this polymer with the biopolymer is that, these polymers
contain functional groups similar to the functional groups present in
biopolymers. [0.5 marks]
• In speciality packaging
• Orthopaedic devices
• In the controlled release of drugs.
(0.5 mark each for any 2 uses. Marks to be awarded for any other correct
answer.)
(c) - These solid wastes seen in the image cause acute environmental problems
and remain undegraded for quite a long time. [0.5 marks]
Q.236 Riya was cleaning her tiffin box after returning home. She used a liquid for the 1
purpose. Which of the following is MOST LIKELY to be present in the liquid used
by Riya?
Q.237 Aparna is a baker. She is preparing a cake for her customer's birthday. The cake 1
will take at least a day or two to reach her customer. Apart from flour, baking
soda and other ingredients, she added salt of propionic acid and alitame. The
probable reason for the last two additions is:
P To defer the expiry of the cake The customer is diabetic and has
asked for restricted sweetness in the
cake
A. P
B. Q
C. S
D. R
Compound T binds itself to a certain point of a cell membrane. The positive end
Q.239 1
of compound T is attracted to the negative end of the cell membrane. Which of
the following identifies compound T, the point on the cell membrane, and the
interaction between them correctly?
A. L
B. M
C. N
Q.240 Prantik plotted the graph showing the rate of activity of an enzyme on a 1
substrate over a certain range of temperatures
.
Four students interpreted the graph as follows:
Student Interpretation
L the rate of the reaction first increases and then decreases with the
rise in temperature.
A. Only student I
B. Both students J and K
C. Only student J
D. Only student L
Q.241 Two statements are given below - one labelled Assertion (A) and the other 1
labelled Reason (R).
Assertion (A): The competitive inhibitors compete with the natural substrate for
their attachment on the allosteric sites of enzymes.
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
Q.242 Two statements are given below - one labelled Assertion (A) and the other 1
labelled Reason (R).
Reason (R): Histamines relax the muscles in the walls of the fine blood vessels.
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
C. (A) is true but (R) is false
D. (A) is false but (R) is true
Q.243 The people from the forest department injected a tiger as it entered a village in 4
search of food. The tiger fell asleep and was carried back to the forest. The
injection contained compound H.
Q.244 Vimla was administered a specific medication after her C-section. Sudipto 2
checked the composition of the medicine and found that one of the ingredients
was obtained from poppy seeds.
(a) What could be the reason for this specific medication being given to Vimla
after the C-section?
(b) Name any two possible effects of this drug if administered in wrong
amounts.
Q.245 (a) State the phenomenon observed in the given image and give a reason for it. 4
(c) How is the glycerol from the saponification reaction above to be extracted?
Q.237 C. S 1
Q.238 B. A: the receptor receives a chemical messenger, B: the shape of the receptor 1
changes after attachment of the messenger, C: the receptor regains structure
after removal of a chemical messenger.
Q.239 D. O 1
Q.242 B. Both (A) and (R) are correct and (R) is not the correct explanation of (A) 1
(b) -This drug inhibits the enzyme which catalyses the dehydration of the
neurotransmitter noradrenaline. [1]
(b) 0.5 marks each for any two of the following effects:
- stupor
- coma
- convulsions
- ultimately death.
Q.245 (a) - When a beam of light is passed through the soap solution the phenomenon 4
observed is the scattering of light. [0.5]
[0.5 marks for the correct name of the alkali;0.5 marks for the reason;1 mark for
the reaction]
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