General Organic Chemistry MCQ Questions & Answers in Organic Chemistry | Chemistry
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281.
Maximum $$-I$$ effect is exerted by the group
A
$$ - {C_6}{H_5}$$
B
$$ - OC{H_3}$$
C
$$ - Cl$$
D
$$ - N{O_2}$$
Answer :
$$ - N{O_2}$$
No explanation is given for this question. Let's discuss the answer together.
282.
Which of the following organic compounds has same hybridisation as its combustion $$\left( {C{O_2}} \right)$$ product?
A
Ethane
B
Ethyne
C
Ethene
D
Ethanol
Answer :
Ethyne
Hybridisation of carbon $$ = s{p^{3 - {\text{number}}\,{\text{of}}\,\pi - bonds}}$$
In $$C{O_2},(\,O\mathop = \limits_{1\pi } C\mathop = \limits_{1\pi } O\,)$$ hybridisation of carbon $$ = s{p^{3 - 2}} = sp$$
In ethyne or acetylene, $${C_2}{H_2},(\,H - C\mathop \equiv \limits^{2\pi } C - H\,\,)$$ hybridisation of carbon $$ = s{p^{3 - 2}} = sp$$
283.
Match the entries of List I with appropriate entries of List II and select the correct answer using the codes given below the lists :
List I (Aromatic compound)
List II (Factor responsible for electrophilic substitution)
P.
$${C_6}{H_5}CH = C{H_2}$$
1.
$$ + E$$ effect
Q.
$${C_6}{H_5}CC{l_3}$$
2.
$$ + M$$ effect
R.
$${C_6}{H_5}OCOC{H_3}$$
3.
Hyperconjugation
S.
$${C_6}{H_5}OH$$ in presence of $$NaOH$$
4.
$$ - I$$ effect
A
P - 1; Q - 2, 3; R - 3; S - 4
B
P - 2; Q - 3, 4; R - 1, 2; S - 1, 2
C
P - 1; Q - 3, 4; R - 3, 4; S - 1, 2
D
P - 2; Q - 1, 2; R - 1, 2; S - 3, 4
Answer :
P - 2; Q - 3, 4; R - 1, 2; S - 1, 2
No explanation is given for this question. Let's discuss the answer together.
284.
Distillation under reduced pressure is generally used to purify those liquids which
A
have very low boiling points
B
are volatile
C
have high boiling points and which decompose below their boiling points
D
have a large difference in their boiling points
Answer :
have high boiling points and which decompose below their boiling points
Compounds which dissociate below their boiling points or which have very high boiling points are distilled under reduced pressure.
285.
Rate of the reaction
is fastest when $$Z$$ is
A
$$O{C_2}{H_5}$$
B
$$N{H_2}$$
C
$$Cl$$
D
$$OCOC{H_3}$$
Answer :
$$Cl$$
$$C{l^ - }$$ Is the best leaving group among the given option.
286.
In which of the following molecules, all atoms are coplanar?
A
B
C
D
Answer :
The molecule in which all the carbon atoms are $$s{p^2}{\text{ - hybridised}}$$ will be coplanar. Thus, in option (A)
i.e.
all carbons are $$s{p^2}{\text{ - hybridised}}{\text{.}}$$
287.
The structure of isobutyl group in an organic compound is
A
B
C
D
Answer :
$$'Iso’$$ mean’s one $$Me$$ group is present in side chain. Hence, the structure of $$iso-butyl$$ group in an organic compound is
( $$'yl’$$ suffix is used to represent one $$-H$$ less than the parent hydrocarbon. )
288.
Due to the presence of an unpaired electron, free radicals are :
A
cations
B
anions
C
chemically inactive
D
chemically reactive
Answer :
chemically reactive
Freeradicals are electrically neutral, unstable and very reactive on account of the presence of odd electrons.
289.
Match the column I with column II and mark the appropriate choice.
A
A - iii, B - iv, C - i, D - ii
B
A - iv, B - iii, C - ii, D - i
C
A - i, B - ii, C - iv, D - iii
D
A - ii, B - iii, C - i, D - iv
Answer :
A - iii, B - iv, C - i, D - ii
No explanation is given for this question. Let's discuss the answer together.
290.
Among the following, the molecule with the highest dipole
moment is :
A
$$C{H_3}Cl$$
B
$$C{H_2}C{l_2}$$
C
$$CHC{l_3}$$
D
$$CC{l_4}$$
Answer :
$$C{H_3}Cl$$
NOTE : Dipole moment is a vector quantity.
Methane molecule being symmetrical, has zero dipole moment. Replacement of one of the $$H - $$ atoms by $$Cl$$ atom increases the dipole moment. The increase in dipole moment is rather more than what can be expected because of the fact that the bond dipole moment of $$C - H$$ bond and that of $$C - Cl$$ bond reinforce one another. Replacement of another $$H$$ atom by $$Cl$$ increases the bond angle due to lone pair - lone pair repulsion
between two $$Cl - $$ atoms thereby reducing the dipole moment of the molecule. Increase in angle is again caused by the the introduction of the third $$Cl - $$ atom. When the fourth $$Cl - $$ atom is introduced, the molecule $$\left( {CC{l_4}} \right)$$ again becomes symmetrical and dipole moment reduces to zero. So, $$C{H_3}Cl$$ will have the maximum dipole moment.