NEET-XII-Chemistry
exam-2 year:2016
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- Qstn #136Hot concentrated sulphuric acid is a moderately
strong oxidizing agent. Which of the following
reactions does not show oxidizing behaviour ?
(1) ``\ce {C + 2H2SO4 \rightarrow CO2 + 2SO2 + 2H2O}``
(2)``\ce { CaF2 + H2SO4 \rightarrow CaSO4 + 2HF}``
(3) ``\ce {Cu + 2H2SO4 \rightarrow CuSO4 + SO2 + 2H2O}``
(4) ``\ce {3S + 2H2SO4 \rightarrow 3SO2 + 2H2O}``digAnsr: 2Ans : (2)
Sol. CaF2 + H2SO4 CaSO4 + 2HF
In this reaction, oxidation number of none of the
atom is not changed. Hence H2SO4 is not acting as
oxidising agent.
- Qstn #137Which of the following pairs of d-orbitals will have
electron density along the axes ?
(1) ``d_{z^2}, d_{x^2-y^2}``
(2)``d_{xy}, d_{x^2-y^2}``
(3) ``d_{z^2}, d_{xz}``
(4) ``d_{xz}, d_{yz}``digAnsr: 1Ans : (1)
Sol. dz2 and dx2-y2 has electron density concentrated on
the axis.
- Qstn #138The correct geometry and hybridization for
XeF4 are :
(1) Planar triangle, ``sp^3d^3``
(2) square planar, ``sp^3d^2``
(3) octahedral, ``sp^3d^2``
(4) trigonal bipyramidal, ``sp^3d^2``digAnsr: 3Ans : (3)
Sol. XeF4, 3 24 2AB L sp d
geometry octahedral
shape square planar
- Qstn #139Among the following which one is a wrong
statement?
(1) ``SeF_4`` and ``CH_4`` have same shape
(2) ``I_3^+`` has bent geometry
(3) ``PH_5`` and ``BiCl_5`` do not exist
(4) ``p\pi-d\pi`` bonds are present in ``SO_2``digAnsr: 1Ans : (1)
Sol. (1) SeF4 -sp3d, lp = 1, shape = see-saw
CH4 -sp3, lp = 0, shape =tetrahedral
(2) +
3I -sp
3, lp =2, shape = bent/angular
(3) PH5 = d-orbital contraction absent
BiCl5 = due to inert pair effect
(Bi+5 act as OA, Cl- act as RA)
(4) SO2 : O=S=O
P-d, P-P both type bonds are present
- Qstn #140The correct increasing order of trans-effect
of the following species is :
(1)``\ce { Br- > CN- > NH3 > C6H5-}``
(2) ``\ce {CN- > Br- > C6H5- >NH3}``
(3) `` \ce {NH3 > CN- > Br- > C6H5-}``
(4)``\ce { CN- > C6H5- > Br- > NH3}``digAnsr: 4Ans : (4)
Sol. Trans effect order - 6 5 3CN C H Br NH
- Qstn #141Which one of the followng statements related to
lanthanons is incorrect ?
(1) All the lanthanons are much more reactive than
aluminium
(2) Ce(+4) solutions are widely used as oxidizing
agent in volumetric analysis
(3) Europium shows +2 oxidation state.
(4) The basicity decreases as the ionic radius
decreases from Pr to Lu.digAnsr: 1Ans : (1)
Sol. (1) Lanthanon's are less reactive than aluminium due
to high IP (Lanthenoid contraction)
(2) Ce+4 is good oxidising agent and easily converted
into Ce+3
(3) Eu(63) = 4f7 5d0 6s2, Eu+2 = 4f7
(4) In lanthenoids series 'Ce' to Lu ionic radius regular
decreases and covalent character increase, basic
character of hydroxide decrease
- Qstn #142Jahn-Teller effect not observed in high
spin complexes of :-
(1) ``d^4``
(2) ``d^9``
(3) ``d^7``
(4) ``d^8``digAnsr: 4Ans : (4)
Sol. John Teller effect explain axial distortion in perfect
octahedral geometry. It is present in d4 high spin,
d7 low spin and d9 configuations which have odd
number of electrons in eg set.
A weak John Teller effect in also present in d7 high
spin complex which has odd number of electrons
in the set.
- Qstn #143Which of the following can be used as the
halide component for Friedel-Crafts reaction ?
(1) Chloroethene
(2) Isopropyl chloride
(3) Chlorobenzene
(4) BromobenzenedigAnsr: 2Ans : (2)
Sol. + CH CH Cl
CH3
3Anhy AlCl
C
H CH3
CH3
cumene
But in chlorobenzene, Bromobenzene, chloroethene
lone pair of halogen are delocalised with bonds,
so attain double bond character.
- Qstn #144In which of the following molecules, all
atoms are coplanar ?
(1)
(2)
(3)
(4)
digAnsr: 3Ans : (3)
Sol.
H H
H
HHHH
H
H H
All carbons are sp2 hybridised
- Qstn #145Which one of the following structures represents
nylon 6,6 polymer ?
(1)
(2)
(3)
(4)
digAnsr: 2Ans : (2)
Sol.
NH2 (CH2)6 NH2
Adipic acid Hexamethylene diamine
C
O
NH (CH2)6 NH n
C
O
(CH2)4
(CH2)4 COOH
Polymerisation
HOOC +
- Qstn #146In pyrrole
The electron density is maximum on :-
(1) 2 and 4
(2) 2 and 5
(3) 2 and 3
(4) 3 and 4digAnsr: 2Ans : (2)
N
H
N
H
N
H
N
H
N
H
(I) (II) (III) (IV) (V)
34
5 2
1
.. + + + +
Maximum electron density at (2) and (5)
as resonating structures III & IV are more stable than
(II) & (V) so are major contributor.
- Qstn #147Which of the following compounds shall not
produced propene by reaction with HBr followed
by elimination of direct only elimination reaction ?
(1) H2C=C=O
(2)
(3)
(4)
digAnsr: 1Ans : (1)
Sol.
CH2 CH2
C
H2
BrH
CH3CH2CH2
Br
Elimination
CH3 CH CH2
BrH Elimination
CH3 CH CH2CH3—CH2—CH2—OH
BrH
CH2 C OH
Br
CH3 C Br
O
CH2=C=O
CH3-CH2-CH2-Br E lim ination CH3-CH=CH2
- Qstn #148Which one of the following nitro-compounds does
not react with nitrous acid ?
(1)
(2)
(3)
(4)
digAnsr: 1Ans : (1)
Sol. 3°-Nitro compound does not react with HNO2
because of absence of -H
- Qstn #149The central dogma of molecular genetics states that
the genetic information flows from :-
(1) DNA `` \rightarrow`` RNA `` \rightarrow`` Proteins
(2) DNA `` \rightarrow`` RNA `` \rightarrow`` Carbohydrates
(3) Amino acids `` \rightarrow`` Proteins `` \rightarrow`` DNA
(4) DNA `` \rightarrow`` Carbohydrates `` \rightarrow`` ProteinsdigAnsr: 1Ans : (1)
Sol. DNA Transcription RNA Translation Protein