Identify a polymer obtained from $\beta$-hydroxybutyric acid and $\beta$-hydroxyvaleric acid.

A conductivity cell dipped in 0.05 MKCl has resistance 600 ohm. If conductivity is $0.0012 \mathrm{ohm}^{-1} \mathrm{~cm}^{-1}$. What is the value of cell constant?

2 moles of an ideal gas are expanded isothermally and reversibly from 20 L to 40 L at 300 K . Calculate work done. ( $\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$).

Identify the product P of following reaction.

$$\mathrm{CH}_3 \mathrm{OH}+\mathrm{CH}_3 \mathrm{MgX} \longrightarrow \mathrm{P}+\mathrm{MgX}\left(\mathrm{OCH}_3\right)$$