Identify the product '$$\mathrm{B}$$' in the following reaction.

Dry ice $$\mathrm{\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{Dry\,ether}^{C{H_3}MgBr}}}$$ A $$\mathrm{\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{dil.\,HCl}^{{H_2}O}}}$$ B

Which among the following reactions exhibits $$\Delta \mathrm{H}=\Delta \mathrm{U}$$ ?

A buffer solution is prepared by mixing 0.2 M sodium acetate and 0.1 M acetic acid. If pK$$_a$$ for acetic acid is 4.7, find the pH.

A solution of nonvolatile solute is obtained by dissolving $$3.5 \mathrm{~g}$$ in $$100 \mathrm{~g}$$ solvent has boiling point elevation $$0.35 \mathrm{~K}$$. Calculate the molar mass of solute.

(Molal elevation constant $$=2.5 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$$ )