What is obtained when calcium acetate is dry distilled?

Identify the name of the reaction: $C_6H_5CH_3 + CrO_2Cl_2 \xrightarrow{CS_2} C_6H_5CH(OCrOHCl_2)_2 \xrightarrow{H_3O^+} C_6H_5CHO$.

The intermediate compound $X$ in the following chemical reaction is :

Which of the following is Rosenmund reduction?

What are $X$ and $Y$ in the following reaction sequence?
$C_5H_{12}O$ $\xrightarrow[573 \ K]{Cu} C_5H_{10}$ $\xrightarrow[\text{(ii) } Zn/H_2O]{\text{(i) } O_3} X + Y$

Which of the following reactions will produce $R-CO-Ar$?