Singlet dichlorocarbene $: CCl X_{2}$ is much less reactive and more selective than singlet $: CH X_{2}$ . The main reason is that

Alone pairs on the chlorine atoms donate into the empty $p$ orbital of the carbene carbon
Bchlorine atoms make the carbene carbon more electron-rich through a $+ I$ effect
Cthe C-Cl bonds are non-polar
D $: CCl X_{2}$ is a triplet with two unpaired electrons

Answer: A

The empty

p

orbital on the carbene carbon of the singlet is the electrophilic site. Chlorine lone pairs overlap with it (a

+ M

effect) and partly fill it, which stabilises the carbene and lowers its reactivity. Chlorine is

- I

, not

+ I

, and

: CCl X_{2}

has a singlet ground state, so the other statements are wrong.