In which of the following reactions is a new carbon-carbon bond not formed?

Which of the following does not react with $NaHSO_3$ (sodium bisulphite)?

The product of which of the following reactions forms a reddish brown precipitate when subjected to Fehling's test?

$CH_3-CO-CH_2-COOH$ $\xrightarrow{\Delta} X$ $\xrightarrow[OH^-]{HCN} Y$,$Y$ is:

The reaction involving the reduction of a ketone to an alkane using zinc amalgam $(Zn-Hg)$ and concentrated hydrochloric acid $(HCl)$ is known as:

Predict the products of the following reactions:
$(i)$ Cyclopentanone + $NH_2OH \xrightarrow{H^+} ?$
(ii) Cyclohexanone + $2,4-DNP \xrightarrow{H^+} ?$
(iii) $R-CH=CH-CHO + NH_2CONHNH_2 \xrightarrow{H^+} ?$
(iv) Acetophenone + $CH_3CH_2NH_2 \xrightarrow{H^+} ?$