Question

Answer the following questions based on the given paragraph.

Stability of carbocation, alkyl free radical and alkene can be explained on the basis of hyperconjugation. In all these cases, there is presence of hydrogen atom at the adjacent carbon atom of $sp^{2}$ hybridised carbon atom. Thotal number of hyperconjugation structures depends upon the number of hydrogen atoms present at adjacent carbon atom of $sp^{2}$C – atom. More the hyperconjugating structures, more is the stability of the ion.

(i) Hyperconjugation is not possible in.

(1) $CH_{3} - CH = CH_{2}$ (2) $CH_{2} = CH_{2}$

(3) (4)

(ii) Decreasing order of stability of following alkenes is.

(i) $CH_{3} - CH = CH_{2}$

(ii) $CH_{3} - CH = CH - CH_{3}$

(iii)

(iv)

• A. (i) > (ii) > (iii) > (iv)
• B. (iv) > (iii) > (ii) > (i)
• C. (iii) > (ii) > (i) > (iv)
• D. (ii) > (iii) > (iv) > (i)

Answer 1

Ans.

(i) (2): Absence of C having hydrogen atom at the adjacent C – atom of double bond.

(ii) (2):

$CH_{3} - CH = CH - CH_{3} > CH_{3} - CH = CH_{2}$