What is the possible product $(P)$ in the following reaction?

The correct order of reactivity of $PhMgBr$ with:
$(I)$ $Ph-CO-Ph$
$(II)$ $CH_3-CHO$
$(III)$ $CH_3-CO-CH_3$
is:

Identify the reagents $S$ and $\mu$ in the scheme below in which $R$ is converted to the nitrile via the benzylic halide. $R, S$ and $\mu$ respectively are:

$H-CDO + H^{18}O^{-} \rightarrow D-C^{18}O^{-} + CH_2D-OH$. The above reaction is known as:

In the following reaction,
$CH_3-C \equiv CH$ $\xrightarrow[H_3O^+]{Hg^{2+}} X$ $\xrightarrow[PhCHO]{dil. NaOH} Y$
$X$ and $Y$,respectively,are

Keto-enol tautomerism is observed in which of the following?