Which of the following reagents can react with both aldehydes and ketones?

Arrange the following compounds in decreasing order of reactivity towards nucleophilic addition reaction:
$(I)$ $C_6H_5COCH_3$
$(II)$ $CH_3COCH_3$
$(III)$ $CH_3CHO$

$3$-hydroxybutanal is formed when $(X)$ reacts with $(Y)$ in a dilute $(Z)$ solution. What are $X, Y$ and $Z$?

The major product $(Z)$ of the following chemical reaction is

$Propanal$ on treatment with dilute sodium hydroxide forms:

Identify the product of the following reaction:
$C_6H_4(CHO)_2 + \text{conc. } NaOH \xrightarrow{\text{heat}} ?$