Identify the product ' B ' in following reaction.

Dry ice $\xrightarrow[\text { dry ether }]{\mathrm{CH}_3 \mathrm{MgBr}} \mathrm{A} \xrightarrow{\mathrm{H}_3 \mathrm{O}^{+}} \mathrm{B}$

Which from following polymers is used to prepare shoe soles?

Half life of a first order reaction is 20 minutes. The time taken to reduce the initial concentration of reactant to $(1 / 10)^{\text {th }}$ is _________

If $\mathrm{E}^{\cdot}\left(\mathrm{Mg}_{(\mathrm{aq})}^{+2} \mid \mathrm{Mg}_{(\mathrm{s})}\right)=-2.37 \mathrm{~V}$. What is potential for $\mathrm{Mg}_{(\mathrm{s})} \longrightarrow \mathrm{Mg}^{+2}(0.01 \mathrm{M})+2 \mathrm{e}^{-}$at 298 K ?