Which of the following reagents can be used for the given chemical transformation?

When liquid $A$ is treated with a freshly prepared ammoniacal silver nitrate solution,it gives a bright silver mirror. The liquid forms a white crystalline solid on treatment with sodium hydrogensulphite. Liquid $B$ also forms a white crystalline solid with sodium hydrogensulphite but it does not give a test with ammoniacal silver nitrate. Which of the two liquids is an aldehyde? Write the chemical equations of these reactions also.

Which of the following compounds,upon hydrolysis followed by heating,gives a product that yields a positive iodoform test?

Identify the product $Y$ in the sequence: $CH_3-CHO + CH_3-MgI$ $\xrightarrow{\text{Ether}} X$ $\xrightarrow{H_2O/H^{+}} Y$

Arrange the following reagents in the correct order in which the above transformation is carried out:

Would you expect $benzaldehyde$ to be more reactive or less reactive in nucleophilic addition reactions than $propanal$? Explain your answer.