Chapter 1

Some Basic Concepts of Chemistry

1. The molality of a urea solution in which 0.0100 g The weight which a 75 kg person would gain if all
of urea, [(NH2)2CO] is added to 0.3000 dm 3 of 1H atoms are replaced by 2H atoms is

water at STP is [AIEEE-2011] [JEE (Main)-2017]

(1) 3.33 × 10–2 m (2) 0.555 m (1) 7.5 kg (2) 10 kg
(3) 5.55 × 10–4 m (4) 33.3 m (3) 15 kg (4) 37.5 kg
2. The density of a solution prepared by dissolving 7. The ratio of mass percent of C and H of an organic
120 g of urea (mol. mass = 60 u) in 1000 g of compound (CXHYOZ) is 6 : 1. If one molecule of the
water of 1.15 g/mL. The molarity of this solution is above compound (CXHYOZ) contains half as much
[AIEEE-2012] oxygen as required to burn one molecule of
compound CXHY completely to CO2 and H2O. The
(1) 1.78 M (2) 1.02 M
empirical formula of compound CXHYOZ is
(3) 2.05 M (4) 0.50 M
[JEE (Main)-2018]
3. The molarity of a solution obtained by mixing
(1) C3H6O3 (2) C2H4O
750 mL of 0.5 (M) HCl with 250 mL of 2 (M) HCl
will be [JEE (Main)-2013] (3) C3H4O2 (4) C2H4O3
(1) 0.875 M (2) 1.00 M 8. A solution of sodium sulfate contains 92 g of Na+
(3) 1.75 M (4) 0.975 M ions per kilogram of water. The molality of Na+ ions
in that solution in mol kg–1 is [JEE (Main)-2019]
4. At 300 K and 1 atm, 15 mL of a gaseous
(1) 16 (2) 4
hydrocarbon requires 375 mL air containing 20%
O2 by volume for complete combustion. After (3) 8 (4) 12
combustion the gases occupy 330 mL. Assuming
9. For the following reaction, the mass of water
that the water formed is in liquid form and the produced from 445 g of C57H110O6 is
volumes were measured at the same temperature
and pressure, the formula of the hydrocarbon is 2C57H110O6 (s) +163O2 (g) o 114CO2 (g) +110H2O(I)
[JEE (Main)-2016]
[JEE (Main)-2019]
(1) C3H8 (2) C4H8
(1) 890 g (2) 490 g
(3) C4H10 (4) C3H6
(3) 445 g (4) 495 g
5. 1 gram of a carbonate (M2CO3) on treatment with
10. The amount of sugar (C 12 H 22O 11) required to
excess HCl produces 0.01186 mole of CO2. The
prepare 2 L of its 0.1 M aqueous solution is
molar mass of M2CO3 in g mol–1 is
[JEE (Main)-2017] [JEE (Main)-2019]
(1) 118.6 (2) 11.86 (1) 136.8 g (2) 17.1 g
(3) 1186 (4) 84.3 (3) 34.2 g (4) 68.4 g
6. The most abundant elements by mass in the body 11. 8 g of NaOH is dissolved in 18 g of H2O. Mole
of a healthy human adult are : fraction of NaOH in solution and molality
(in mol kg–1) of the solution respectively are
Oxygen (61.4%); Carbon (22.9%); Hydrogen
(10.0%) and Nitrogen (2.6%). [JEE (Main)-2019]

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(1) 0.2, 22.20 (2) 0.167, 22.20 18. 25 g of an unknown hydrocarbon upon burning
produces 88 g of CO 2 and 9 g of H 2O. This
(3) 0.167, 11.11 (4) 0.2, 11.11
unknown hydrocarbon contains
12. The percentage composition of carbon by mole in
[JEE (Main)-2019]
methane is [JEE (Main)-2019]
(1) 22 g of carbon and 3 g of hydrogen
(1) 80% (2) 75%
(2) 24 g of carbon and 1 g of hydrogen
(3) 20% (4) 25%
(3) 20 g of carbon and 5 g of hydrogen
13. For a reaction, N2 (g) + 3H2 (g) o 2NH3 (g).
(4) 18 g of carbon and 7 g of hydrogen
Identify dihydrogen (H2) as a limiting reagent in the
following reaction mixtures. [JEE (Main)-2019] 19. Amongst the following statements, that which was
not proposed by Dalton was [JEE (Main)-2020]
(1) 35 g of N2 + 8 g of H2
(1) All the atoms of a given element have identical
(2) 28 g of N2 + 6 g of H2
properties including identical mass. Atoms of
(3) 56 g of N2 + 10 g of H2 different elements differ in mass
(4) 14 g of N2 + 4 g of H2 (2) Matter consists of indivisible atoms.
14. What would be the molality of 20% (mass/mass) (3) Chemical reactions involve reorganization of
aqueous solution of KI? (molar mass of atoms. These are neither created nor
KI = 166 g mol–1) [JEE (Main)-2019] destroyed in a chemical reaction.

(1) 1.48 (2) 1.51 (4) When gases combine or reproduced in a

chemical reaction they do so in a simple ratio
(3) 1.08 (4) 1.35
by volume provided all gases are at the same
15. The minimum amount of O2(g) consumed per gram T & P.
of reactant is for the reaction:
20. A solution of two components containing
(Given atomic mass : Fe = 56, O = 16, Mg = 24, n1 moles of the 1st component and n2 moles of the
P = 31, C = 12, H = 1) [JEE (Main)-2019] 2nd component is prepared. M1 and M2 are the
(1) 2Mg(s) + O2(g) o 2MgO(s) molecular weights of component 1 and 2
respectively. If d is the density of the solution in g
(2) 4Fe(s) + 3O2(g) o 2Fe2O3(s) mL–1, C2 is the molarity and x2 is the mole fraction
(3) C3H8(g) + 5O2(g) o 3CO2(g) + 4H2O(I) of the 2nd component, then C2 can be expressed
as [JEE (Main)-2020]
(4) P4(s) + 5O2(g) o P4O10(s)
16. The mole fraction of a solvent in aqueous solution 1000 x 2
(1) C 2 =
of a solute is 0.8. The molality (in mol kg–1) of the M1 + x 2 (M2 -M1 )
aqueous solution is [JEE (Main)-2019]
(1) 13.88 × 10–2 (2) 13.88 × 10–3 1000 d x 2
(2) C 2 = M + x (M -M )
(3) 13.88 (4) 13.88 × 10–1 1 2 2 1

17. 5 moles of AB2 weigh 125 × 10–3 kg and 10 moles

d x2
of A2B2 weigh 300 × 10–3 kg. The molar mass (3) C2 = M + x (M -M )
2 2 2 1
of A(MA) and molar mass of B(MB) in kg mol–1
are [JEE (Main)-2019]
d x1
(1) MA = 25 × 10–3 and MB = 50 × 10–3 (4) C2 = M + x (M -M )
2 2 2 1
(2) MA = 50 × 10–3 and MB = 25 × 10–3
21. The average molar mass of chlorine is
(3) MA = 5 × 10–3 and MB = 10 × 10–3
35.5 g mol–1. The ratio of 35Cl to 37Cl in naturally
(4) MA = 10 × 10–3 and MB = 5 × 10–3 occurring chlorine is close to [JEE (Main)-2020]

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(1) 1 : 1 (2) 2 : 1 31. The formula of a gaseous hydrocarbon which

(3) 3 : 1 (4) 4 : 1 requires 6 times of its own volume of O 2 for
complete oxidation and produces 4 times its own
22. Ferrous sulphate heptahydrate is used to fortify
volume of CO2 is CxHy. The value of y is ______.
foods with iron. The amount (in grams) of the salt
required to achieve 10 ppm of iron in [JEE (Main)-2021]
100 kg of wheat is________. [JEE (Main)-2020]
32. Complete combustion of 1.80 g of an oxygen
Atomic weight : Fe = 55.85; S = 32.00; O = 16.00 containing compound (CxHyOz) gave 2.64 g of CO2
23. NaClO3 is used, even in spacecrafts, to produce and 1.08 g of H2O. The percentage of oxygen in
O2. The daily consumption of pure O2 by a person the organic compound is : [JEE (Main)-2021]
is 492 L at 1 atm, 300 K. How much amount of
(1) 50.33 (2) 53.33
NaClO3, in grams, is required to produce O2 for the
daily consumption of a person at 1 atm, 300 K? (3) 51.63 (4) 63.53
__________. [JEE (Main)-2020]
33. The number of significant figures in 50000.020 × 10–3
NaClO3(s) + Fe(s) o O2(g) + NaCl(s) + FeO(s) is ________. [JEE (Main)-2021]
R = 0.082 L atm mol–1 K–1 34. The NaNO3 weighed out to make 50 mL of an
24. The molarity of HNO 3 in a sample which has aqueous solution containing 70.0 mg Na+ per mL
density 1.4 g/mL and mass percentage of 63% is is __________ g. (Rounded off to the nearest
_____. (Molecular Weight of HNO3 = 63) integer)
[JEE (Main)-2020] [Given : Atomic weight in g mol–1 - Na : 23; N :
25. The ratio of the mass percentages of ‘C & H’ and 14; O : 16] [JEE (Main)-2021]
‘C & O’ of a saturated acyclic organic compound
35. A 6.50 molal solution of KOH (aq.) has a density
‘X’ are 4 : 1 and 3 : 4 respectively. Then, the moles
of 1.89 g cm–3. The molarity of the solution is ___
of oxygen gas required for complete combustion of
two moles of organic compound ‘X’ is ________. mol dm–3. (Round off to the Nearest Integer).

[JEE (Main)-2020] [Atomic masses : K : 39.0 u; O : 16.0 u; H : 1.0 u]

26. The mole fraction of glucose (C 6H 12O 6) in an [JEE (Main)-2021]

aqueous binary solution is 0.1. The mass 36. Complete combustion of 750 g of an organic
percentage of water in it, to the nearest integer, is
compound provides 420 g of CO2 and 210 g of
________ [JEE (Main)-2020]
H2O. The percentage composition of carbon and
27. 6.023 × 1022 molecules are present in 10 g of a hydrogen in organic compound is 15.3 and
substance ‘x’. The molarity of a solution containing _____respectively. (Round off to the Nearest
5 g of substance ‘x’ in 2 L solution is ______
Integer). [JEE (Main)-2021]
× 10–3. [JEE (Main)-2020]
37. When 35 mL of 0.15 M lead nitrate solution is
28. The mass of ammonia in grams produced when 2.8
kg of dinitrogen quantitatively reacts with 1 kg of mixed with 20 mL of 0.12 M chromic sulphate
dihydrogen is _______. [JEE (Main)-2020] solution, ________ × 10–5 moles of lead sulphate
precipitate out. [JEE (Main)-2021]
29. The minimum number of moles of O2 required for
complete combustion of 1 mole of propane and 2 (Round off to the Nearest Integer).
moles of butane is _______. [JEE (Main)-2020]
38. The number of chlorine atoms in 20 mL of chlorine
30. 4.5 g of compound A (MW = 90) was used to make gas at STP is _______ 1021. (Round off to the
250 mL of its aqueous solution. The molarity of the Nearest integer). [JEE (Main)-2021]
solution in M is x × 10–1. The value of x is _____.
(Rounded off to the nearest integer) [Assume chlorine is an ideal gas at STP

[JEE (Main)-2021] R = 0.083 L bar mol–1K–1, NA = 6.023 × 1023]

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39. Complete combustion of 3 g of ethane gives 48. The molarity of the solution prepared by dissolving 6.3
x × 1022 molecules of water. The value of x is g of oxalic acid (H2C2O4˜2H2O) in 250 mL of water in
________. mol L–1 is x × 10–2. The value of x is _______.
(Round off to the Nearest Integer). (Nearest integer)
[Use : NA = 6.023 × 1023 ; [Atomic mass : H : 1.0, C : 12.0, O : 16.0]
Atomic masses in u : C : 12.0 ; O : 16.0 ; H : 1.0]
[JEE (Main)-2021]
[JEE (Main)-2021]
49. Sodium oxide reacts with water to produce sodium
40. 250 mL of 0.5 M NaOH was added to 500 mL of hydroxide. 20.0 g of sodium oxide is dissolved in 500
1 M HCI. The number of unreacted HCI molecules in
mL of water. Neglecting the change in volume, the
the solution after complete reaction is ______ ×1021.
concentration of the resulting NaOH solution is _____
(Nearest integer) (NA = 6.022 × 1023)
× 10–1 M. (Nearest integer)
[JEE (Main)-2021]
[Atomic mass : Na = 23.0, O = 16.0, H = 1.0]
41. If the concentration of glucose (C6H12O6) in blood is
0.72 g L–1, the molarity of glucose in blood is [JEE (Main)-2021]
________ × 10–3 M. (Nearest integer)
50. If 80 g of copper sulphate CuSO4˜5H2O is dissolved in
(Given : Atomic mass of C = 12, H = 1, O = 16 u) deionised water to make 5 L of solution. The
[JEE (Main)-2021] concentration of the copper sulphate solution is x ×
42. Consider the complete combustion of butane, the 10–3 mol L–1. The value of x is _______.
amount of butane utilized to produce 72.0 g of water [Atomic masses Cu : 63.54 u, S : 32 u, O : 16 u,
is ____ × 10–1 g. (in nearest integer)
H : 1 u] [JEE (Main)-2021]
[JEE (Main)-2021]
51. The number of atoms in 8 g of sodium is x × 1023. The
43. The number of significant figures in 0.00340 is _______. value of x is _____. (Nearest integer)
[JEE (Main)-2021]
[Given : NA = 6.02 × 1023 mol–1
44. The density of NaOH solution is 1.2 g cm–3. The
molality of this solution is ______ m. Atomic mass of Na = 23.0 u] [JEE (Main)-2021]

(Round off to the Nearest Integer) 52. If a rocket runs on a fuel (C15H30) and liquid oxygen,
the weight of oxygen required and CO2 released for
[Use : Atomic masses : Na : 23.0 u, O : 16.0 u
H : 1.0 u Density of H2O : 1.0 g cm–3] every litre of fuel respectively are:

[JEE (Main)-2021] (Given : density of the fuel is 0.756 g/mL)

45. An aqueous KCl solution of density 1.20 g ml–1 has [JEE (Main)-2022]
a molality of 3.30 mol kg–1. The molarity of the
(1) 1188 g and 1296 g
solution in mol L–1 is _____. (Nearest integer)
[Molar mass of KCl = 74.5] [JEE (Main)-2021] (2) 2376 g and 2592 g

46. 100 mL of Na 3PO 4 solution contains 3.45 g (3) 2592 g and 2376 g
of sodium. The molarity of the solution is _____ (4) 3429 g and 3142 g
× 10–2 mol L–1. (Nearest integer)
53. The number of N atoms in 681 g of C7H5N3O6 is
[Atomic Masses - Na : 23.0 u, O : 16.0 u, P : 31.0 u]
x × 1021. The value of x is ______. (NA = 6.02 × 1023
[JEE (Main)-2021] mol–1) (Nearest Integer)
47. 100 g of propane is completely reacted with
[JEE (Main)-2022]
1000 g of oxygen. The mole fraction of carbon dioxide
in the resulting mixture is x × 10–2. The value of x is 54. A protein ‘A’ contains 0.30% of glycine (molecular
_____. (Nearest integer) weight 75). The minimum molar mass of the protein
[Atomic weight : H = 1.008; C = 12.00; O = 16.00] ‘A’ is _______ × 103 g mol–1 [nearest integer]
[JEE (Main)-2021] [JEE (Main)-2022]

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55. A commercially sold conc. HCl is 35% HCl by mass. 60. Compound A contains 8.7% Hydrogen, 74% Carbon
If the density of this commercial acid is 1.46 g/mL, and 17.3% Nitrogen. The molecular formula of the
the molarity of this solution is : compound is,
(Atomic mass : Cl = 35.5 amu, H = 1 amu) Given : Atomic masses of C, H and N are 12, 1 and
[JEE (Main)-2022] 14 amu respectively.

(1) 10.2 M (2) 12.5 M The molar mass of the compound A is 162 g mol–1.

(3) 14.0 M (4) 18.2 M [JEE (Main)-2022]

56. CNG is an important transportation fuel. When (1) C4H6N2 (2) C2H3N
100 g CNG is mixed with 208 g oxygen in vehicles, (3) C5H7N (4) C10H14N2
it leads to the formation of CO2 and H2O and produced
large quantity of heat during this combustion, then 61. Using the rules for significant figures, the correct
the amount of carbon dioxide, produced in grams is 0.02858 u 0.112
_____. [nearest integer] answer for the expression will be
0.5702
[Assume CNG to be methane]
[JEE (Main)-2022]
[JEE (Main)-2022]
(1) 0.005613 (2) 0.00561
57. The moles of methane required to produce 81 g of
(3) 0.0056 (4) 0.006
water after complete combustion is _____ × 10–2
mol. [nearest integer] 62. 56.0 L of nitrogen gas is mixed with excess of
hydrogen gas and it is found that 20 L of ammonia
[JEE (Main)-2022]
gas is produced. The volume of unused nitrogen gas
58. Given below are two statements : one is labelled as is found to be ____ L. [JEE (Main)-2022]
Assertion (A) and the other is labelled as Reason
(R). 63. Chlorophyll extracted from the crushed green leaves

Assertion (A) : At 10°C, the density of a 5 M solution was dissolved in water to make 2 L solution of Mg of
of KCl [atomic masses of K & Cl are 39 & 35.5 g concentration 48 ppm. The number of atoms of Mg
mol–1 respectively], is ‘x’ g ml–1. The solution is in this solution is x × 1020 atoms. The value of x is
cooled to –21°C. The molality of the solution will ________. (Nearest integer)
remain unchanged.
(Given : Atomic mass of Mg is 24 g mol–1; NA = 6.02 ×
Reason (R) : The molality of a solution does not
1023 mol–1) [JEE (Main)-2022]
change with temperature as mass remains
unaffected with temperature. 64. When 800 mL of 0.5 M nitric acid is heated in a
beaker, its volume is reduced to half and 11.5 g of
In the light of the above statements, choose the
correct answer from the options given below. nitric acid is evaporated. The molarity of the

[JEE (Main)-2022] remaining nitric acid solution is x × 10–2 M. (Nearest

(1) Both (A) and (R) are true and (R) is the integer)
correct explanation of (A). (Molar mass of nitric acid is 63 g mol–1)
(2) Both (A) and (R) are true but (R) is not the [JEE (Main)-2022]
correct explanation of (A).
(3) (A) is true but (R) is false. 65. Haemoglobin contains 0.34% of iron by mass. The

(4) (A) is false but (R) is true. number of Fe atoms in 3.3 g of haemoglobin is

59. Two elements A and B which form 0.15 moles of (Given : Atomic mass of Fe is 56 u, NA = 6.022 × 1023
A2B and AB3 type compounds. If both A2B and AB3
weigh equally, then the atomic weight of A is _____ mol–1) [JEE (Main)-2022]
times of atomic weight of B.
(1) 1.21 × 105 (2) 12.0 × 1016
[JEE (Main)-2022]
(3) 1.21 × 1020 (4) 3.4 × 1022
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66. In the given reaction, (1) H2, 1.42 moles

(2) H2, 0.71 moles

X  Y  3Z R XYZ3
(3) N2, 1.42 moles
if one mole of each of X and Y with 0.05 mol of Z
gives compound XYZ3. (Given : Atomic masses of (4) N2, 0.71 moles
X, Y and Z are 10, 20 and 30 amu, respectively.) the
yield of XYZ3 is _______ g. (Nearest integer) 70. Consider the reaction
[JEE (Main)-2022]
4HNO3 (l)  3KCl(s)
67. On complete combustion of 0.492 g of an organic
compound containing C, H and O, 0.7938 g of CO2 o Cl2 (g)  NOCl(g)  2H2O(g)  3KNO3 (s)
and 0.4428 g of H 2 O was produced. The %
composition of oxygen in the compound is _______. The amount of HNO3 required to produce 110.0 g of
[JEE (Main)-2022] KNO3 is
68. 2 L of 0.2 M H2SO4 is reacted with 2 L of 0.1 M
NaOH solution, the molarity of the resulting product (Given : Atomic masses of H, O, N and K are 1, 16,
Na 2SO 4 in the solution is _______ millimolar. 14 and 39 respectively.) [JEE (Main)-2022]
(Nearest integer) [JEE (Main)-2022] (1) 32.2 g

69. N2(g)  3H2(g) U 2NH3(g) (2) 69.4 g

20 g 5g
(3) 91.5 g
Consider the above reaction, the limiting reagent of
the reaction and number of moles of NH3 formed (4) 162.5 g
respectively are : [JEE (Main)-2022]

‰‰‰

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