MCQs on Alkene

Alkenes are unsaturated hydrocarbons. There is at least one C-C double bond present in alkenes. The general formula of an alkene is CnH2n. They are also known as olefins due to oil forming nature. Due to weak pi bond and loosely held electrons, alkenes are readily attacked by electrophilic reagents.

1. Which of the following compounds react most readily with Br(g)?

(a) C2H2

(b) C3H6

(c) C2H4

(d) C4H10

2. When propene reacts with HBr in the presence of peroxide, it gives rise to

(a) allyl bromide

(b) isopropyl bromide

(c) n-propyl bromide

(d) 3-bromopropane

3. Find the alkene with maximum stability

(a) cis-2-Butene

(b) trans-2-Butene

(c) 1-Butene

(d) All have the same stability

4. Ethylene bromide on treatment with Zn gives

(a) Alkyne

(b) Alkene

(c) Alkane

(d) All of the above

5. Which of the following reactions is common in alkenes?

(a) Addition

(b) Elimination

(c) Substitution

(d) Superposition

6. Cis-trans isomerism in alkenes is due to

(a) chiral carbon

(b) free rotation about single bond

(c) free rotation about double bond

(d) restricted rotation about double bond

7. Baeyer’s reagent is used to detect

(a) glucose

(b) double bonds

(c) oxidation

(d) reduction

8. Which of the following will form 2 acetaldehyde molecules on ozonolysis?

(a) 1-pentene

(b) 2-pentene

(c) 1-butene

(d) 2-butene

9. Which of the following reagents will form 1-propanol from propene?

(a) B2H6, H2O2, OH

(b) Aq. KOH

(c) H2O, H2SO4

(d) Hg(OAc)2, NaBH4/H2O

10. Geometrical isomerism is exhibited by

(a) 2-Butene

(b) 2-Butyne

(c) 2-Butenol

(d) Butanol

Answer

1. (b)

2. (c)

3. (b)

4. (b)

5. (a)

6. (d)

7. (b)

8. (d)

9. (a)

10. (a)

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