[oceanmd]

Which are the least stable and most chemically reactive compounds?

a. CH3CH2CH2CH3      
b.CH3CH double bond CHCH3
c.CH3C triple bond CCH3
d.CH3 four bonds C

I think the correct answer is c, because triple bond makes the compound more reactive by addition across triple bond.
I also think that compound d cannot exist because C has only 4 covalent bonds

Please correct me if I am wrong. Thank you

[Fluorine]

a. CH3CH2CH2CH3      
b.CH3CH double bond CHCH3
c.CH3C triple bond CCH3
d.CH3 four bonds C

Why is d H₃C(4)C, if it's four bonds wouldn't it be C(4)C and not H₃C(4)C, where (4) expresses a quadruple bond? Either way I would say "d" is the most reactive/unstable. It's not a unheard of concept (dicarbon) though it probably would not last long - at all.

Single bond = sigma
Double bond = sigma and pi
Triple bond = sigma, pi, and pi
Quadruple bond = sigma, pi, pi, and sigma

[oceanmd]

but d is not C(4)C, it is H3C(4)C