Dry heating of calcium acetate gives

In the following sequence of reactions,what is the end product $(D)$?
$C_2H_5Br$ $\xrightarrow{KCN} A$ $\xrightarrow{H_3O^{+}} B$ $\xrightarrow{LiAlH_4} C$ $\xrightarrow[573 \ K]{Cu} D$.

Identify $Z$ in the following sequence of reactions.
$C_2H_4Br_2$ $\xrightarrow[\text{(ii) } NaNH_2]{\text{(i) alc- } KOH} X$ $\xrightarrow[\text{Red hot}]{\text{Fe tube, } 873 \ K} Y$ $\xrightarrow[\Delta]{\left(CH_3CO\right)_2O / \text{Anhyd-} AlCl_3} Z$

Which of the following reagents is most suitable for the conversion of $R-CH_2OH$ to $RCHO$?

In the Rosenmund's reduction,$BaSO_4$ taken with catalyst $Pd$ acts as

The reagents used in the Etard reaction $(I)$ and the Stephen reaction $(II)$ are: