Identify the major products $(P)$ and $(Q)$ respectively for the given reaction.

When $but-3-en-2-ol$ reacts with aqueous $HBr$,the product formed is:

The number of possible isomeric products formed when $3$-chloro-$1$-butene reacts with $HCl$ through carbocation formation is $.............$.

$A$ (organic compound) $+ O_2 \to X + Y + Z$. Compound $(A)$ in pure form does not give a precipitate with $AgNO_3$ solution. $A$ mixture containing $70\%$ of $(A)$ and $30\%$ of ether is used as an anaesthetic. Compound $(X)$ and $(Y)$ are oxides while $(Z)$ is a pungent smelling gas. $(X)$ is a neutral oxide which turns cobalt chloride paper pink. Compound $(Y)$ turns lime water milky and produces an acidic solution with water. Compounds $(A), (X), (Y)$ and $(Z)$ respectively will be:

The products $(A)$ and $(B)$ respectively are:

Which one of the following compounds will be most reactive for $S_N1$ reactions?