1
MCQ (Single Correct Answer)

NEET 2017

The correct statement regarding electrophile is
A
electrophile is a negatively charged species and form a bond by accepting a pair of electrons from another electrophile
B
electrophiles are generally neutral species and can form a bond by accepting a pair of electrons from a nucleophile
C
electrophile can be either neutral or positively charged species and can form a bond by accepting a pair of electrons from a nucleophile
D
electrophile is a negatively charged species and can form a bond by accepting a pair of electrons from a nucleophile.

Explanation

Electrophile can be either neutral or positively charged species and can form a bond by accepting a pair of electrons from a nucleophile.
2
MCQ (Single Correct Answer)

NEET 2016 Phase 1

For the following reactions :

(A)  CH3CH2CH2Br + KOH $$ \to $$
                 CH3CH $$=$$ CH2 + KBr + H2O

Which of the following statements is correct?
A
(A) is elimination, (B) and (C) are substitution reactions.
B
(A) is substitution, (B) and (C) are addition reactions.
C
(A) and (B) are elimination reactions and (C) is addition reaction.
D
(A) is elimination, (B) is substitution and (C) is addition reaction.

Explanation

(A) Saturated compound is converted into unsaturated compound by removal of group of atoms hence, it is an elimination reaction.

(B) —Br group is replaced by —OH group hence, it is a substitution reaction.

(C) Addition of Br2 converts an unsaturated compound into a saturated compound hence, it is an addition reaction.
3
MCQ (Single Correct Answer)

NEET 2016 Phase 2

Which among the given molecules can exhibit tautomerism?
A
III only
B
Both I and III
C
Both I and II
D
Both II and III

Explanation

$$\alpha $$-hydrogen at bridge carbon never participates in tautomerism. Thus, only (III) exhibits tautomerism.
4
MCQ (Single Correct Answer)

AIPMT 2015 Cancelled Paper

Consider the following compounds :

Hyperconjunction occurs in
A
III only
B
I and III
C
I only
D
II only

Explanation

Only structure (III) has $$\alpha $$-H in conjugation with free radical.

So, hyperconjugation is possible in III only.

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