Which of the following statements are correct about HCN and HCP?

(P) HCN is linear with triple bond between carbon and nitrogen 

(Q) HCP does not exist because P does not form triple bond due to large size

(R) In HCP molecule two a-bond and two n bonds are present

 (S) Carbon atom is sp hybridized in HCN

Because of its size, P cannot form a triple bond, hence HCP does not exist. This claim is untrue since phosphorous does not have a tendency to make numerous bonds with itself and instead has a relatively big size, which reduces the extent of "(3p - 3p)" overlap that can lead to "pi-bond" formation. Phosphorus hence does not exist as a "P 2" molecule. Option is the right response, therefore (d).