
SECTION-A
61. The order of relative stability of the contributing
structure is:
CH =CH–
2 C–H
I
O
CH – CH = C – H
2II
O
CH – CH = C – H
2III
O
Choose the correct answer from the options given
below:
(1) I > II > III
(2) II > I > III
(3) I = II = III
(4) III > II > I
Ans. (1)
Sol. I > II > III, since neutral resonating structures are
more stable than charged resonating structure. II > III,
since stability of structure with –ve charge on more
electronegative atom is higher.
62. Which among the following halide/s will not show
SN1 reaction:
(A) H2C = CH – CH2Cl
(B) CH3 – CH = CH – Cl
(C)
(D)
Choose the most appropriate answer from the
options given below:
(1) (A), (B) and (D) only
(2) (A) and (B) only
(3) (B) and (C) only
(4) (B) only
Ans. (4)
Sol. Since
is very unstable, CH3–CH =
CH – Cl cannot give
reaction.
63. Which of the following statements is not correct
about rusting of iron?
(1) Coating of iron surface by tin prevents rusting,
even if the tin coating is peeling off.
(2) When pH lies above 9 or 10, rusting of iron
does not take place.
(3) Dissolved acidic oxides SO2, NO2 in water act
as catalyst in the process of rusting.
(4) Rusting of iron is envisaged as setting up of
electrochemical cell on the surface of iron
object.
Ans. (1)
Sol. As tin coating is peeled off, then iron is exposed to
atmosphere.
64. Given below are two statements:
Statement (I) : In the Lanthanoids, the formation
of Ce+4 is favoured by its noble gas configuration.
Statement (II) : Ce+4 is a strong oxidant reverting
to the common +3 state.
In the light of the above statements, choose the
most appropriate answer from the options given
below:
(1) Statement I is false but Statement II is true
(2) Both Statement I and Statement II are true
(3) Statement I is true but Statement II is false
(4) Both Statement I and Statement II are false
Ans. (2)
Sol. Statement (1) is true, Ce+4 has noble gas electronic
configuration.
Statement (2) is also true due to high reduction
potential for Ce4+/Ce3+ (+1.74V), and stability of
Ce3+, Ce4+ acts as strong oxidizing agent.
65. Choose the correct option having all the elements
with d10 electronic configuration from the following:
(1) 27Co, 28Ni, 26Fe, 24Cr
(2) 29Cu, 30Zn, 48Cd, 47Ag
(3) 46Pd, 28Ni, 26Fe, 24Cr
(4) 28Ni, 24Cr, 26Fe, 29Cu
Ans. (2)
Sol. [Cr] = [Ar]4s1 3d5
[Cd] = [Kr]5s24d10
[Cu] = [Ar]4s13d10
[Ag] = [Kr]5s14d10
[Zn] = [Ar]4s23d10