1
MCQ (Single Correct Answer)

NEET 2017

The IUPAC name of the compound
A
5-formylhex-2-en-3-one
B
5-methyl-4-oxohex-2-en-5-al
C
3-keto-2-methylhex-5-enal
D
3-keto-2-methylhex-4-enal

Explanation

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

The enolic form of ethyl accetoacetate as shown below has
A
9 sigma bonds and 2 pi-bonds
B
9 sigma bonds and 1 pi-bond
C
18 sigma bonds and 2 pi-bonds
D
16 sigma bonds and 1 pi-bond.

Explanation

The given structure has 18$$\sigma $$ bonds and 2$$\pi $$ bonds.

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