Chemistry - GOC Question with Solution | TestHub

All three are tertiary cyclopentyl cations stabilised by hyperconjugation. A C-H bond is a better σ donor than a C-D bond (C-D has the lower zero-point energy and is harder to break).

(b) has CH₃ : strongest hyperconjugation.

(a) has CD₃ : weaker.

(c) has CD₃ and one more D in the ring α-position : weakest.

Order : b > a > c.