Arrange the following compounds in increasing order of their reactivity in nucleophilic addition reaction :
$(P)$ Benzaldehyde
$(Q)$ $p-$Tolualdehyde
$(R)$ $p-$Nitrobenzaldehyde
$(S)$ Acetophenone

The major product formed in the following reaction is:

$C_{7}H_{10}O$ reacts with $CH_{3}MgBr$ to give a compound $C_{8}H_{12}O$ which gives a positive iodoform test. Identify the structure of $A$.

Toluene $\xrightarrow[(2) \ H_3O^{+}]{(1) \ CrO_2Cl_2 / CS_2} X$ $\xrightarrow{\text{Conc. } NaOH} Y + Z$. The correct statements about $Y$ and $Z$ are:
$A. \quad Y$ is a secondary alcohol
$B. \quad Y$ is the reduction product of $X$
$C. \quad Z$ on heating with soda lime gives benzene
$D. \quad Y$ does not give $H_2$ gas with $Na$ metal

Which of the following compounds will not show tautomerism?

In the reaction sequence $C_6H_5-CH(OH)-CH_2-C(=O)-CH_3 \xrightarrow{(i) NaOBr, (ii) H_2O/H^{+}, (iii) \Delta}$ product,the product will be: