Given below are two statements :

Statement I : One mole of propyne reacts with excess of sodium to liberate half a mole of $\mathrm{H}_2$ gas.

Statement II : Four g of propyne reacts with $\mathrm{NaNH}_2$ to liberate $\mathrm{NH}_3$ gas which occupies 224 mL at STP.

In the light of the above statements, choose the most appropriate answer from the options given below :

The incorrect statement regarding ethyne is

Identify the product A and product B in the following set of reactions.

Given below are two statements :

Statement (I) : $$\mathrm{S}_{\mathrm{N}} 2$$ reactions are 'stereospecific', indicating that they result in the formation of only one stereo-isomer as the product.

Statement (II) : $$\mathrm{S}_{\mathrm{N}} 1$$ reactions generally result in formation of product as racemic mixtures.

In the light of the above statements, choose the correct answer from the options given below :