What is the volume of one particle in BCC structure if ' $a$ ' is edge length?

Identify product ' B ' in following reaction.

$$\mathrm{CH}_3-\mathrm{I}+\mathrm{KCN} \longrightarrow \mathrm{~A} \xrightarrow[\substack{\mathrm{C}_2 \mathrm{H}_2 \mathrm{OH} \\}]{\mathrm{Na}} \mathrm{B} $$

Which of the following alkenes does NOT exhibit cis-trans isomerism?

Carbonated water is an example of a solution of