Which of the following is NOT prepared by the action of Grignard's reagent on methanal?

Which following reagent is used in Etard reaction?

Which of the following compounds is obtained by Rosenmund reduction of benzoyl chloride?

Identify product '$$B$$' in following sequence of reactions.

2n Propanone $$\mathrm{\buildrel {Ba{{(OH)}_2}} \over \longrightarrow}$$ A $$\mathrm{\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{ - {H_2}O}^\Delta }}$$ nB