Alkadienes Questions & Answers on Organic Chemistry

1. Identify the incorrect statement regarding alkadiene.

a) These are acyclic acids
b) These are unsaturated hydrocarbons
c) These compounds have only one C=C bonds
d) These compounds have the general formula CnH2n-2

Answer: c

Explanation: Alkadiene compounds have a minimum of two double bonded carbon atoms but they can have more than two.

2. Alkadienes are classified into how many types?

a) 1
b) 2
c) 3
d) 4

Answer: c

Explanation: Based on the position and location of the double bonds, they are classified into three types.

3. Identify the incorrect statement regarding conjugated double bonds in alkadiene.

a) 1,3 alkadienes have conjugated double bond
b) Compounds with a double bond exhibit this type of bond
c) 1,3 pentadiene is an example for this bond
d) The conjugated dienes have properties similar to that of alkenes

Answer: b

Explanation: Compounds with alternative double and single bonds exhibit this kind of bond.

4. Identify the one which is the perfect example for Isolated double bond?

a) 1,4 pentadiene
b) 1,2 pentadiene
c) 1,3 pentadiene
d) 1,5 butadiene

Answer: a

Explanation: Only the 1,4 alkadiene compounds exhibit isolated double bonds.

5. Identify the incorrect statement regarding alkadienes.

a) Dienes show cis-trans isomerism
b) Conjugated dienes have better stability compared to other dienes
c) Dienophile supports alkadienes
d) Alkadienes also undergo hydrobromination

Answer: c

Explanation: Dienophiles attack the performance of alkadienes rather than supporting them.

6. Conjugated diene reacts with which among the following to form a cyclohexene?

a) Phenol
b) Dienophile
c) Hexane
d) Tribromo phenol

Answer: b

Explanation: Dienophile on reaction with conjugated dienes forms cyclohexene and this reaction is known as Diels-alder reaction.

7. Which among the following dienes undergo addition with the help of radical-chain mechanism?
a) Cumulated dienes
b) Isolated dienes
c) Simple dienes
d) Conjugated dienes

Answer: d

Explanation: Conjugated dienes undergoes addition reactions and the product usually formed are 1,4 dienes.

8. Identify the statement which is related to Diels-Alder reaction?

a) It is very stereospecific
b) Molecular distortion takes place
c) Cyclic dienes react very slow than the linear chain dienes
d) Addition of maleic anhydride to cyclopentadiene causes diene and dienophile to produce different products

Answer: c

Explanation: Cyclic dienes are more reactive than linear chain dienes.

9. A molecule in which more than one single bond separates two double bonds are called as ______

a) Coordinate bond
b) Isolated double bond
c) Cumulative double bond
d) Conjugated double bond

Answer: b

Explanation: As per the definition of isolation, a double bond is separated by more than a single bond.

10. Isolated dienes are similar in property to _____

a) Monoolefins
b) Diolefins
c) Triolefins
d) Tetraolefins

Answer: a

Explanation: Isolated dienes behave more like monoolefins and have properties similar to them.

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