Question

Question #e668c

Answer 1

In terms of `C-H` bond-length, `C-=C-H` is LESS than `=C-H`, is less than `R_3C-H`..........

Explanation:

And note that this order of bond-lengths, derives from actual experimental values, i.e.

`-=C-H_"acetylene"`, `1.20xx10^-10*m`; `=C-H_"ethylene"`, `1.35xx10^-10*m`; `R_3C-H_"methane"`, `1.54xx10^-10*m`.

We would expect (i) that as the carbon becomes less saturated, the `C-H` bond would become shorter in that more electron density is localized between the carbon and hydrogen nuclei. Unsaturation (ii) also relieves steric congestion about a carbon centre, and works to the same end.