Heating a mixture of silver powder and $CHCl_3$ yields which compound?

What is obtained by the reaction of calcium carbide with heavy water?

$A$ salt-producing hydrocarbon among these compounds is

In the following reaction sequence: $Ph-CH=CH-Ph$ $\xrightarrow{Br_2/CCl_4} (A)$ $\xrightarrow{2NaNH_2} (B)$ $\xrightarrow{H_2/Pd-CaCO_3} (C)$,the product $(C)$ is:

Reactant $P$ (an alkyne) gives products $Q$ (trans-alkene) or $R$ (cis-alkene).
The possible reagents are:
$(I) \ 2Na/liq. NH_3$
$(II) \ H_2/Pd/CaCO_3$ (quinoline)
$(III) \ 2H_2/Pd/C$
Which of the following statements is/are correct with respect to the above conversion?

Which of the following reactions forms an aldehyde as a product?