Which reaction is suitable for the preparation of $\alpha$-chloroacetic acid?

The product obtained when acetic acid is treated with phosphorus trichloride is

The major product in the following reaction is:

What is the catalyst used in the conversion of acetaldehyde to acetic acid?

An aldehyde on oxidation gives:

Grignard reagent $RMgBr$ $(P)$ reacts with water and forms a gas $(Q)$. One gram of $Q$ occupies $1.4 \ dm^3$ at $STP$. $(P)$ on reaction with dry ice in dry ether followed by $H_3O^{+}$ forms a compound $(Z)$. $0.1 \ mole$ of $(Z)$ will weigh . . . . . . $g$. (Nearest integer)