Treatment of propionaldehyde with dil. $NaOH$ gives:

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

An alkene $(A)$ $C_{16}H_{16}$ on ozonolysis gives only one product $(B)$ $C_8H_8O$. $(B)$ can also be obtained by the hydrolysis of the product obtained from the reaction between cyanobenzene and $CH_3MgBr$. $(A)$ shows geometrical isomerism and decolourises $Br_2$ water. $(B)$ on treatment with $SeO_2$ produces $(C)$. Which statement is not correct about $(B)$?

The $Wolff-Kishner$ reduction is used for which of the following?

The reaction of phthalaldehyde with concentrated $NaOH$ produces:

The increasing order of the reactivity of the following compounds in nucleophilic addition reaction is:
Propanal,Benzaldehyde,Propanone,Butanone