Organic Chemistry MCQ with Answers

Organic Chemistry MCQ with Answers

116) Osmium tetraoxide is used for:

Answer is:

Hydroxylation of alkenes to give syn−addition

117) Dehydration of cyclopenylcarbinol with conc. H₂SO₄ forms:

Answer is:

Cyclohexene

118) In water, H−O−H bond angle is 104.5^o, but in ethers (R−O−R), the C−O−C bond angle is about 110^o. The reason to justify it, is:

Answer is:

Distortion caused by the lone pair of oxygen atom is more than compensated by the bulky alkyl groups

Explanation:

Bulky groups counter balance the repulsion caused by the lone pairs.

119) In the reaction of phenol with CHCl₃ and aqueous NaOH at 70^oC, the electrophile attacking the ring is:

Answer is:

:CCl₂

120) An aromatic ether is not cleaved by HI even at 525 K. The aromatic ether is:

Answer is:

C₆H₅OC₆H₅

Explanation:

Due to greater electronegativity of sp² hybridised carbon atoms of the benzene ring, dialkyl ethers are not attacked by nucleophiles like I⁻.

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