NARAYANA IIT ACADEMY JEE MAIN – 2013 - Narayana Group

Sol. Benzyl and allyl carbocations are more stable due to resonance.
43. Consider the following reaction:
2
2
z
xMnO4 yC2O4
zH xMn 2yCO
2
H2O
2
The values of x, y and z in the reaction are, respectively:
(1) 5, 2 and 16 (2) 2, 5 and 8 (3) 2, 5 and 16 (4) 5, 2 and 8
Ans. (3)
Sol.
2
2MnO 5C O 16H
4 2 4
2
2Mn 10CO2 8H2O
x = 2
y = 5
z = 16.
44. Which of the following is the wrong statement?
(1) ONCl and ONO – are not isoelectronic (2) O 3 molecule is bent
(3) Ozone is violet-black in solid state (4) Ozone is diamagnetic gas
Ans. No Answer
Sol. All the four given statements are correct.
45. A gaseous hydrocarbon gives upon combustion 0.72 g. of water and 3.08 g. of CO 2 . The
empirical formula of the hydrocarbon is:
(1) C 2 H 4 (2) C 3 H 4 (3) C 6 H 5 (4) C 7 H 8
Ans. (4)
Sol. No. of mole of H 2 O = 0.72 0.04 mole
18
No. of mole of H = 2 × 0.04 = 0.08 mole
No. of mole of CO 2 = 3.08 0.07 mole
44
No. of mole of ‘C’ = 0.07 mole
No. of mole of C 0.07 7
No. of mole of H 0.08 8
Empirical Formula = C 7 H 8 .
46. In which of the following pairs of molecules / ions, both the species are not likely to exist?
2
2
2
2
(1) H
2
, He2
(2) H
2
, He2
(3) H
2
, He2
(4) H
2
, He2
Ans. (3)
Sol.
Species Bond order
H 1
2 [1 0] 0.5
2
He 2 1 2 [4 2] 1
2
NARAYANA IIT ACADEMY JEE MAIN – 2013