WBJEE 2014 Chemistry Question Paper With Solutions
WBJEE 2014 Chemistry Question Paper With Solutions
WBJEE 2014 Chemistry Question Paper With Solutions
com
WBJEEM - 2014 (Answers & Hints)
1
Chemistry
Code-
(A) (C)
Four gases P, Q, R and S have almost same values of b but their a values (a, b are van der Waals constants) are in the order Q < R < S < P. At a particular temperature among the four gases the most easily liquefiable one is (A) P Ans : (A) (B) Q (C) R (D) S
Hints : More the value of a for the gas, more i the intermolecular forces of attraction. Thus the gas can be easily liquefied. 3. emission is always accompanied by (C) 4. (A) formation of antineutrino and particle formation of antineutrino and -ray (B) emission of particle and -ray
w m w
(B)
Ans : (C)
The values of H and S of a certain reaction are 400 kJ mol1 and 20 kJ mol1K1 respectively. The temperature below which the reaction is spontaneous is (A) 100K 20C (C) 20K (D) 120C
Ans : (C) Hints : The reaction is spontaneous when G is -ve G < 0 H T S < 0 400 (T) (20) < 0 400 + 20T < 0 20T < 400
T< 400 ; T < 20K 20
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(D) remains unchanged
e
1.
During the emission of a positron from a nucleus, the mass number of the daughter element remains the same but the atomic number (B) is decreased by 2 units
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WBJEEM - 2014 (Answers & Hints)
2
Chemistry
5.
OH
OH
OH
OH I
(A) (C)
OH
OH III
(B) only I and II are chiral (D) only I and III are chiral
OH
OH H R R OH
H I
R S H OH II
OH
S
S H
OH III
PPh3 Br
1. n-BuLi
2. CH2= O
PPh3 O
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J
PPh3 O
(B)
(C)
PPh3
O
(D)
PPh3
w m w
CH2= O PPh3
+
Hints : 7.
PPh3 H
Bu
PPh3 O
Among the following compounds, the one(s) that gives (give)effervescence with aqueous NaHCO3 solution is (are) (CH3CO)2O I (A) I and II (B) CH3COOH II I and III PhOH III (C) only II (D) CH3COCHO IV I and IV
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WBJEEM - 2014 (Answers & Hints)
3
Chemistry
8.
The system that contains the maximum number of atoms is (A) 4.25 g of NH3 (B) 8 g of O2 (C) 2 g of H2 (D) 4 g of He
Ans : (C)
4 d) 4 g He = NA = NA atoms 4
9. Metal ion responsible for the Minamata disease is (A) Co2+ (B) Hg2+ (C) Cu2+ (D) Zn2+
Ans : (B)
10. Among the following observations, the correct one that differentiates between SO32 and SO42 is (A) (B) (C) (D) Both form precipitate with BaCl2, SO32 dissolves in HCl but SO42 does not SO32 forms precipitate with BaCl2, SO42 does not SO42 forms precipitate with BaCl2, SO32 does not
Both form precipitate with BaCl2, SO42 dissolves in HCl but SO32 does not
Ans : (A)
BaCl2 + SO32 BaSO3 + 2Cl 11. The pH of 104 M KOH solution will be Ans : (D)
pH + pOH = 14, pH = 14 - 4 = 10 12. The reagents to carry out the following conversion are
Me Me Me
w m w
(A)
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(B)
11
(C) 10.5
(D)
10
(A) (C)
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WBJEEM - 2014 (Answers & Hints)
4
Chemistry
CH3 C C H
NaNH2
+ Ch3 C C : Na
CH3 I
Tautomerization CH 3 C = C CH 3 H OH
13. The correct order of decreasing H-C-H angle in the following molecules is
H H H H
H I II
H III
(A)
(B)
(D)
Ans : (B)
H 115 H I
14.
Cf was formed along with a neutron when an unknown radioactive substance was bombarded with 6C12. The unknown substance was
98
246
(A)
91
Pa234
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H H H 120 109.5 H H H II III
(B)
90
Th234
(C)
92
U235
(D)
92
U238
Ans : (C)
A 12 246 + 0 n1 Hints : z X + 6 C 98 Cf
z + 6 = 98 z = 92
A + 12 = 246 + 1
or, A = 247 12
= 235
15. The rate of a certain reaction is given by, rate = k [H+]n. The rate increases 100 times when the pH changes from 3 to 1. The order (n) of the reaction is (A) 2 (B) 0 (C) 1 (D) 1.5 Ans : (C) Hints : Rate r = k[H+]n New rate, r = 100 r pH changes from 3 to 1 i.e. [H+] = 103M changes to [H+] = 101M i.e. conc. increases 100 times
r [H+ ] = + r [H ]
n
w m w
[H+ ] [H+ ]
101 103
= 100
or, n = 1
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WBJEEM - 2014 (Answers & Hints)
5
Chemistry
16. (32Ge76, 34Se76) and (14Si30, 16S32) are examples of (A) isotopes and isobars (C) isotones and isotopes Ans : (B) Hints :
( (
32 Ge
76
30 32 14 Si , 16 Se
A Z = 30 14 = 16 Same no. of neutrons = isotones and 32 16 = 16 17. The enthalpy of vaporization of a certain liquid at its boiling point of 35C is 24.64 kJ mol-1. The value of change in entropy for the process is (B) 80 J K1mol1 (C) 24.64 J K1mol1 (D) 7.04 J K1mol1 (A) 704 J K1mol1 Ans : (B) Hints : S =
qrev T At constant pressure, qrev = Htransformation
S vap = Hvap Tb
18. Given that : C + O2 CO2 ; H = x kJ 2CO + O2 2CO2 ; H = y kJ The heat of formation of carbon monoxide will be (A)
y 2x 2
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; Tb = boiling point, Hvap = Enthalpy of vapourizati n (B) y + 2x (C)2x y
(D)
2x y 2
Ans : (A) Hints : i) C + O2 CO2 ; H = x kJ ii) 2CO + O2 2CO2 ; H = y kJ Eq (i) 2 2C + 2O2 2CO2 H = 2 x kJ Writing eq. (ii) in rever e order 2CO2 2CO + O2, H = y kJ
w m w
(D)
12
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WBJEEM - 2014 (Answers & Hints)
6
Chemistry
Hints : 10 volume H2O2 means 1 mL H2O2 solution produces 10 mL O2 at STP 2H2O2 2H2O + O2 2 mol 1 mol 2 34 g 22.4 L at STP 68 g 22400 mL O2 at STP is produced from 68 g. H2O2
68 10 g = 0.03036 g H O 2 2 22400 1 mL H2O2 solution contains 0.03 g H2O2 (approx.) 100 mL H2O2 solution contains 0.03 100 = 3 g H2O2 (approx.) 20. In DNA, the consecutive deoxynucleotides are connected via (A) phospho diester linkage (B) phospho monoester linkage (C) phospho triester linkage (D) amide linkage Ans : (A)
10 mL O2 is produced from
Hints :
Phosphodiester linkage
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CH2 O
21. The reaction of aniline with chloroform under alkaline conditions leads to the formation of (A) Phenyl cyanide (B) Phenyl isonitrile (C) Phenyl cyanate (D) Ans : (B)
NH2
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O
O=P=O
CH2
N-base
O=P=O O
N-base
Phenyl isocyanate
NC
Hints :
+ CHCl3 + KOH
Isonitrile
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WBJEEM - 2014 (Answers & Hints)
7
Chemistry
22. The reagent with which the following reaction is best accomplished is
Me Me
+N Cl 2
(B)
Me
H3PO3
(C)
H3PO4
(D)
NaHSO3
Hints :
+N Cl
2
23. At a certain temperature the time required for the complete diffusion of 200 mL of H2 gas is 30 minutes. The time required for the complete diffusion of 50 mL of O2 gas at the same temperature will be (A) 60 minutes (B) 30 minutes (C) 45 minutes (D) 15 minutes Ans : (B)
Me
2 3 4 5
Me
1
Hints :
Me
Hints :
V T
26. An atomic nucleus having low n/p ratio tries to find stability by (B) the emission of a positron (A) the emission of an particle (C) capturing an orbital electron (K-electron capture) (D) emission of a particle Ans : (B) Hints : B and C both option are correct but as single option, B is more appropriate. 27. The correct order of decreasing length of the bond as indicated by the arrow in the following structure is
+ I + II + + III
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(B)
25. For one mole of an ideal gas the slope of V vs T curve at constant pressure of 2 atm is X lit mol1K1. The value of the ideal universal gas constant R in term of X is (A) X lit atm mol1K1 (B) X/2 lit a m mol1K1 (C) 2X lit atm mol1K1 (D) 2X atm lit1mol1K1 Ans : (C)
R R T , m = = X , or R = X.P, = 2X L.atm mol1K1 P P (m is the slope)
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Me Me Me Me
4 32 200 t O2 t O2 , t = 30 min = = or 4 = O2 30 2 30 50
PV = RT, V =
II>I>III
(C)
III>II>I
(D)
I>III>II
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WBJEEM - 2014 (Answers & Hints)
+ + CH2 C CH2 CH2 C CH2 B.O=1.5 CH3 CH3 + + + + 4 II: CH2 C CH2 CH2 C CH2 H2CCCH2 B.O. = = 1.33 3 CH2 CH2 CH2 + + + III: CH2 CH2 C = CH2 B.O is slightly greater than one due to hyper conjugation CH
3
8
Chemistry
Hints : I:
28. If Cl2 is passed through hot aqueous NaOH, the products formed have Cl in different oxidation states. These are indicated as (C) +1 and +5 (D) 1 and +3 (A) 1 and +1 (B) 1 and +5 Ans : (B)
+ 3H2O Hints : Reaction : 3Cl2 + 6NaOH (hot & conc) 5 NaCl + NaClO 3 29. In the following reaction, the product E is
CHO CHO 1. NaOH + 2. H E
CH2OH
1 +5
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CO2H
CO2H
(A)
CH2OH CHO
CHO
CO2H
(B)
(C)
(D)
CO2H
CHO
CHO
1. NaOH 2. H
CH2OH CO2H
30. The amount of electrolytes required to coagulate a given amount f Ag colloidal solution (ve charge) will be in the order (A) (C) NaNO3 > Al2(NO3)3 > Ba(NO3)2 (B) Al2(NO3)3 > Ba(NO3)2 > NaNO3 ( ) NaNO3 > Ba(NO3)2 > Al2(NO3)3 Al2(NO3)3 > NaNO3 > Ba(NO3)2
Ans : (D)
Hints : For [AgI] Negatively charged sol, e fec ive i n for coagulation is cation and amount of electrolyte required
1 . Also note that Al(NO3)3 is written as Al2(NO3)3 in the questions paper. charge content
31. The value of H for cooling 2 mole of n deal monoatomic gas from 225C to 125C at constant pressure will be given Cp = (A)
250 R
w m w
(B)
5 R] 2
500 R
(C) 500 R
(D)
250 R
Ans : (B)
Hints : Here, n = 2
5 R 2 T = 125 225 = 100
Cp =
5 R (100) = 500 R 2 32. The quantity of electricity needed to separately electrolyze 1M solution of ZnSO4, AlCl3 and AgNO3 completely is in the ratio of
H = nCp T = 2 (A) 2:3:1 (B) 2:1:1 (C) 2 : 1 : 3 (D) 2:2:1 Ans : (A) Hints : Zn2+ + 2e Zn Al2+ + 3e Al
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WBJEEM - 2014 (Answers & Hints)
9
Chemistry
Ag+ + e Ag Quantity of electricity required = 2 : 3 : 1 33. The emission spectrum of hydrogen discovered first and the region of the electromagnetic spectrum in which it belongs, respectively are (A) Lyman, ultraviolet (B) Lyman, visible (C) Balmer, ultraviolet (D) Balmer, visible Ans : (D) Hints : Fact 34. As per de Broglies formula a macroscopic particle of mass 100 gm and moving at a velocity of 100 cm s1 will have a wavelength of (A) 6.6 1029 cm (B) 6.6 1030 cm (C) 6.6 1031 cm (D) 6.6 1032 cm Ans : (C) Hints : m = 100 g, =
v = 100 cm s1 = 1 ms1
Ans : (B) Hints : Cu : z = 29 [Ne] 3s23p63d104s1 36. The compound that will have a permanent dipole moment among he following is
H H
Cl Cl
Cl
H
II
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H Cl Cl Br B Cl Cl Cl
(B) III II IV (C) III
Cl H Cl net Cl H net= 0 Cl Cl Br Cl net= 0 Br net= 0
h 6.626 10 34 = = 6.626 1033 m = 6.626 1031 cm mv 0.1 1 35. The electronic configuration of Cu is (A) Ne3s23p63d94s2 (B) Ne3s23p63d104s1 (C) Ne3s23p63d34s24p6
(D)
Ne3s23p63d54s24p4
(D)
IV
Cl Cl
37. Among the following structures the one which is not a resonating structure of others is
w m w
O Me Me O
(B) II II
O Me O
I (A) I Ans : (D)
O Me
O Me O
O Me
III (C) III
O Me O
IV
(D)
IV
O Me
Hints :
O () CH2
A hydrogen is removed from this carbon. But, in resonating structure, position of atoms do not changes.
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WBJEEM - 2014 (Answers & Hints)
10
Chemistry
(A) Reaction M is faster and less exothermic than Reaction N (B) Reaction M is slower and less exothermic than Reaction N (C) Reaction M is faster and more exothermic than Reaction N (D) Reaction M is slower and more exothermic than Reaction N Ans : (C) Hints : Reaction M is faster than N. Activation energy (EM < EN)
39. An amine C3H9N reacts with benzene sulfonyl chloride to form a white pr cipitate which is insoluble in aq. NaOH. The amine is
Me
(A) Ans : (B)
Me N Me
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Me
(B)
Me
(D)
N H
Me
(C)
Me
NH2
Me NH2
Me
Hints : Me
N H
Me + Cl S
Me N S
+ HCl
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Insoluble
40. Among the followings, the one which is not a greenhouse gas, is (A) N2O Ans : (D) Hints : O2 is not a green house gas 41. The number of amino acids and number of peptide bonds in a linear tetrapeptide (made of different amino acids) are respectively (A) 4 and 4 (B) 5 and 5 (C) 5 and 4 (D) 4 and 3 Ans : (D) (B) CO2 (C) CH4 (D) O2
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WBJEEM - 2014 (Answers & Hints)
o R H 1
11
Chemistry
R o
H 2
R o
H 3
R
H 4 o
No. of amino acids = 4 No. of Peptide bonds = 3 42. The 4th higher homologue of ethane is (A) Butane (B) Pentane Ans : (C) Hints : homologus differ by CH2 unit
4th homologue of ethene is C6H14
(C)
Hexane
(D)
Heptane
{C2H6 + ( CH2 )4 }
; E 0 F e + + + /Fe + + = 0.7120 V
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(B) 0.3125 V (C) 1.114 V
43. The hydrides of the first elements in groups 15 - 17, namely NH3, H2O and HF respectively show abnormally high values for melting and boiling points. This is due to (A) small size of N, O and F (B) the ability to form extensive intramolecular H-bonding (C) the ability to form extensive intramolecular H-bonding (D) effective van der Walls interaction Ans : (B) Hints : NH3, H2O and HF form extensive intermolecular Hydrogen bonding due to high ionic potential of N, O and F. 44. The two half cell reactions of an electrochemical cell is given as
(D)
1.114 V
Ag+ + e Ag
0.3995 V (cathode )
E cell= 0.3125 V
45. In case of heteronuclear diatomics of the type AB, where A is more electronegative than B, bonding molecular orbital resembles the character of A more than that of B. The statement (A) is false (B) is true (C) can not be evaluated since data is not sufficient (D) is true only for certain systems Ans : (B) Hints :
Energy B A (more electronegetive) Bonding molecular orbital resembles A more closely
w m w
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WBJEEM - 2014 (Answers & Hints)
12
Chemistry
CATEGORY - II Q.46 to Q.55 carry two marks each, for which only one option is correct. Any wrong answer will lead to deduction of 2/3 mark 46. The order of decreasing ease of abstraction of Hydrogen atoms in the following molecule is
Hb
Ha
Me
(A)
Ha > Hb > Hc
(C) Hb > Ha > Hc (D) Hc > Hb > Ha Ans : (B) Hints : The more stable is the radical formed after H atom abstraction, easier is the abstraction
Me Me
w m w
47. The bond angle in NF3(102.3) is smaller than NH3(107.2). This is because of (A) large size of F compared to H (B) large size of N compared to F (C) opposite polarity of N in the two molecules (D) small size of H compared to N Ans : (C) Hints : In NF3, dipole moment vector point in the direction of F. Thus electron cloud shifts towards F in NF bond. This reduces bond pair-bond pai r pulsi n in NF and hence a decrease in bond angle FNF. 48. The compressibility factor (Z) of one mole of a van der Waals gas of negligible a value is (A) 1 (B)
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radical after Ha abstraction (tertiary allyl radical) radical after Hb abstraction (secondary radical) Me stability order of free adical is 3 allyl > 2 allyl > 2 a kyl radical after Hc abstraction (secondary allyl adica
Ha>Hc >Hb
bp RT
(C)
1+
bp RT
(D)
bp RT
(D)
9 104 M
Ans : (D)
150 C2 0.007 ( 0.3 ) = 0.3 Ka = = = 9 104 M . 500 1 1 0.3 Here, cant be neglected w.r.t 1 due to large value
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WBJEEM - 2014 (Answers & Hints)
13
Chemistry
50. A piece of wood from an archaeological sample has 5.0 counts min1 per gram of C-14, while a fresh sample of wood has a count of 15.0 min1 gram1. If half life of C-14 is 5770 years, the age of the archaeological sample is (C) 10,000 years (D) 11,000 years (A) 8,500 years (B) 9,200 years Ans : (B) Hints :
2.303 ( log3 )( 5770 ) [ Activity of fresh sample ] 0.693 t = 2.303log 15 0.693 yrs t = 2.303 log , t= 5770 5 0.693 t1 [ Activity of fossil]
2
= 9,200 Yrs (approx) 51. When phenol is treated with D2SO4/D2O, some of the hydrogens get exchanged. The final product in this exchange reaction is
OD D
(A)
OD D
(B)
OD
H H
(C)
OD H
(D)
H D
H D
H H
D H
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O O H H D2SO4 D2O D D OD
OD D D
D 52. To observe an elevation of boiling point of 0 05C, the amount of solute (Mol. Wt. = 100) to be added to 100 g of water (Kb=0.5) is (A) 2 g (B) 0.5 g (C) 1 g (D) 0.75 g Ans : (C) 0.5x 10 ; X = 1 g. Hints : Tb = Kb m, 0.05 = .5 X 0.05= 100 53. The structure of XeF6 is experimentally determined to be distorted octahedron. Its structure according to VSEPR theory is (A) Octahedron (B) Trigonal bipyramid (C) Pentagonal bipyramid (D) Tetragonal bipyramid Ans : (C) Hints : Xe is surrounded by 6 bond pairs and one lone pair. The geometry (geometry of electron pairs) is pentagonal bipyramid. 54. The most likely protonation site in the following molecule is 4 3 Me 5 1
w m w
2 Me
(A) C-1 Ans : (A) (B) C-2
6 8 7 (C) C-3
(D) C-6
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WBJEEM - 2014 (Answers & Hints)
14
Chemistry
Me
Hints :
+ Aromatic as well as tartiary carbocation Me 55. The volume of ethyl alcohol (density 1.15 g/cc) that has to be added to prepare 100 cc of 0.5 M ethyl alcohol solution in water is
(A) 1.15 cc (B) 2 cc (C) 2.15 cc (D) 2.30 cc
Ans : (B) Hints : Mass of ethyl alcohol before and after the preparation must be equal. x(volume in cc)
56. Cupric compounds are more stable than their cuprous counterparts in solid state. This is because (A) (B) (C) (D) the endothermic character of the 2nd I P of Cu is not so high size of Cu2+ is less than Cu+
the lattice energy released for cupric compounds is much higher than Cu+
Ans : (A, B, D)
Hints : Actually 2nd IP of Cu (1958 kJ/mol) is not very high as compared to 1st IP (745 kJ/mol). In addition the gain in lattice energy due to +2 state and small size f Cu favour the divalent state in the solid. 57. Among the following statements about the m lec les X and Y, the one (s) which is (are) correct is (are) CHO CHO H OH H HO
w m w
(A) (C)
Ans : (B, C, D) Hints : X and Y are mirror images of each other. They are aldohexoses too. In X, OH of the asymmetric C farthest from CHO is on the right, so it is D-Sugar. Y , on the other hand, has OH on the left. Thus it is a L-sugar. 58. For a spontaneous process, the correct statement(s) is (are) (A) (C) (Gsystem)T, P>0 (Gsystem)T, P<0 (B) (D) (Ssystem) + (Ssurroundings) > 0 (Usystem)T, V > 0
Ans : (B, C) Hints : Spontaneity of of the process can be expressed either by taking entropy changes of system and surrounding together or by considering free energy change of the system alone at constant temperature and pressure. The known criteria are : (Gsys)T, P < 0 and (Ssys) + (Ssur)> 0
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HO H H H OH OH H HO HO OH H H CH2OH X CH2OH
Q.56 to Q.60 carry two marks each, for which one or more than one options may be correct. Marking of correct options will lead to a maximum mark of two on pro rata basis. There will be no negative marking for these questions. However, any marking of wrong option will lead to award of zero mark against the respective question irrespective of the number of correct options marked.
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WBJEEM - 2014 (Answers & Hints)
15
Chemistry
59. The formal potential of Fe3+/Fe2+ in a sulphuric acid and phosphoric acid mixture (E=+0.61V) is much lower than the standard potential (E=+0.77V). This is due to (A) (C) formation of the species [FeHPO4]+ formation of the species [FeSO4]
+
(B) lowering of potential upon complexation (D) high acidity of the medium
Ans : (A, B, D) Hints : Formation of complex by Fe3+ reduces its concentration. Thereby lowers the formal reduction potential. 60. Two gases X (Mol. Wt. Mx) and Y(Mol. Wt. MY; MY > Mx) are at the same temperature T in two different containers. Their root mean square velocities are CX and CY respectively. If the average kinetic energies per molecule of two gases X and Y are Ex and EY respectively, then which of the following relation (s) is (are) true? (A) (C) Ex > EY Ex = EY = (B) C x > CY
3 RT 2
(D) EX= EY =
3 kT 2 B
Ans : (B, D)
w m w
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Hints : For same temperature, higher the molar mass, lower is the rms velocity.KE of individual molecules is expressed in terms of KB not R