Chemistry
Assertion (A): Alkynes show addition reactions.
Reason (R): Alkanes show substitution reactions.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true but R is not the correct explanation of A.
Explanation— Alkynes contain a carbon–carbon triple bond, making them highly unsaturated; therefore they readily take part in addition reactions with hydrogen, halogens, etc. Hence, the assertion (A) is true.
Alkanes, being saturated hydrocarbons, usually react by substitution, for example, the replacement of a hydrogen atom by chlorine in the presence of ultraviolet light. Hence, the reason (R) is true.
While both statements are correct, the fact that alkanes undergo substitution does not explain why alkynes undergo addition, hence, reason (R) is not the correct explanation of assertion (A).
Related Questions
Which of the following molecule contains C=C bond between adjacent carbon atoms ?
P — C4H8
Q — C3H4
R — C3H6
- Only P
- Only R
- Both P and R
- Both P and Q
Assertion (A): Carbon shows catenation.
Reason (R): Catenation is the property of self linking by covalent bonds.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): The members of a homologous series can be prepared by using the same general method.
Reason (R): The members of a homologous series have the same physical properties.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): The brown colour of bromine fades when it is added to ethylene.
Reason (R): Ethylene shows substitution reactions.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.