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Basics of Organic Chemistry (GOC)

NEET Chemistry · 63 questions · Page 5 of 7 · Click an option or "Show Solution" to reveal answer

Q41
The IUPAC name of the following compound is
A trans-2-chloro-3-iodo-2-pentene
B cis-3-iodo-4-chloro-3-pentane
C trans-3-iodo-4-chloro-3-pentene
D cis-2-chloro -3-iodo-2-pentene.
Correct Answer
Option A
Solution

∴\therefore IUPAC name is trans-2-chloro-3-iodo-2-pentene.

Q42
Considering the state of hybridization of carbon atoms, find out the molecule among the following which is linear ?
A CH 3 −- CH == CH −- CH 3
B CH 3 −- C≡ \equiv C −- CH 3
C CH 2 == CH −- CH 2 −- C≡ \equiv CH
D CH 3 −- CH 2 −- CH 2 −- CH 3
Correct Answer
Option B
Solution

The carbon atoms which have sp hybridization form a linear molecule.

Among the given compounds, has sp hybridized carbon atoms which has bond angle 180 o are attached to sp 3 hybridised carbon atoms.

So, it is linear.

Q43
The correct IUPAC name for the compound is
A 4-ethyl-3-propylhex-1-ene
B 3-ethyl-4-ethenylheptane
C 3-ethyl-4-propylhex-5-ene
D 3-(1 -ethylpropyl)hex- 1 -ene.
Correct Answer
Option A
Solution

4-ethyl-3-propylhex-1-ene

Q44
The IUPAC name of the compound CH 3 CH==CHC≡ \equiv CH is
A pent-4-yn-2-ene
B pent-3-en-1-yne
C pent-2-en-4-yne
D pent-1-yn-3-ene
Correct Answer
Option B
Solution

If a molecule contains both carbon-carbon double or triple bonds, those two are treated as per in seeking the lowest number combination.

However, if the sum of numbers turns out to be the same starting from either of the carbon chain, then lowest number is given to the C = C double bond.

Q45
Which of the following species is not electrophilic in nature?
A C+l\mathop C\limits^ + l
B BH 3
C H 3 O+\mathop O\limits^ +
D N+\mathop N\limits^ + O 2
Correct Answer
Option C
Solution

H 3

O+\mathop O\limits^ +

has a lone pair of electrons on oxygen atom, thus it is not an electrophile. Also the octet is complete

Q46
The IUPAC name of the compound having the formula CH≡ \equiv C−-CH==CH 2 is
A 1-butyne-3-ene
B but-1-yne-3-ene
C 1-butene-3-yne
D 3-butene-1-yne.
Correct Answer
Option C
Solution

Since the sum of numbers starting from either side of the carbon chain turns out to be the same, so lowest number is given to the C = C end.

Q47
The stability of carbanions in the following. is in the order of
A (iv) > (ii) > (iii) > (i)
B (i) > (iii) > (ii) > (iv)
C (i) > (ii) > (iii) > (iv)
D (ii) > (iii) > (iv) > (i)
Correct Answer
Option C
Solution

The carbonion which have more s-character will be more stable.

Thus, the order of stability is : (i) > (ii) > (iii) > (iv)

Q48
How many stereoisomers does this molecule have? CH 3 CH==CHCH 2 CHBrCH 3
A 8
B 2
C 4
D 6
Correct Answer
Option C
Solution

Both geometrical isomerism (cis-trans form) and optical isomerism is possible in the given compound.

No. of optical isomer = 2 n = 2 1 = 2 (where n = no. of asymmetric carbon) Hence total no. of stereoisomers = 2 + 2 = 4

Q49
Base strength of is in the order of
A (i) > (iii) > (ii)
B (i) > (ii) > (iii)
C (ii) > (i) > (iii)
D (iii) > (ii) > (i)
Correct Answer
Option B
Solution

Weaker the acid, strongest is its conjugate base.

Among alkane, alkene and alkyne, alkyne are most acidic and alkanes are least acidic, so the order of base strength is : (i) > (ii) > (iii)

Q50
The order of decreasing reactivity towards an electrophilic reagent, for the following would be (i) benzene (ii) toluene (iii) chlorobenzene (iv) phenol
A (ii) > (iv) > (i) > (iii)
B (iv) > (iii) > (ii) > (i)
C (iv) > (ii) > (i) > (iii)
D (i) > (ii) > (iii) > (iv)
Correct Answer
Option C
Solution

Benzene having any activating group, i.e., OH, R etc. undergoes electrophilic substitution very easily as compared to benzene itself.

Thus, toluene (C 6 H 5 CH 3 ) and phenol (C 6 H 5 OH) undergo electrophilic substitution very readily than benzene.

Chlorine with +E and +M effect deactivates the ring due to strong –I effect.

So, it is difficult to carry out the substitution in chlorobenzene than in benzene, so correct order is (iv) > (ii) > (i) > (iii)

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