The valancy of carbons is generally `4`, but its oxidation state may be `-4, -2, 0, +2, -1`, etc. In the compounds containing `C, H`, and `O`, the oxidation number of `C` is calculated as
Oxidation number of `C= (2n_(O)-n_(H))/(n_(C ))`
Where `n_(O), n_(H)` and `n_(C )` are the numbers of oxygen, hydrogen, and carbons, atoms, respectively.
In which of the following compounds is the valency of `C` two?

Options

A. Ketenes
B. Alkenes
C. Allenes
D. Carbenes

Answer

D

Explanation

a. `H_(2)C=C=O`(Ketenes)(Valency of `C=4`)
b. `R_(2)(C )=CR_(2)`(alkenes) (Valency of `C=4`)
c. `H_(2)C=C=CH_(2)`(Allenes) (Valency of `C=4)`
d. `:CH_(2)` (Carbenes) (Valency of `C=2`)