$A$ in the above reaction is:

The reddish brown precipitate formed in the Fehling's test for aldehydes $(RCHO)$ is due to the formation of

An organic compound $X$ is oxidised by using acidified $K_2Cr_2O_7$ solution. The product obtained reacts with phenyl hydrazine but does not give the silver mirror test. The compound $X$ is,

$A$ well-known reagent which contains copper sulphate,sodium potassium tartrate,and sodium hydroxide is

The major products of the following reaction are:

Oxidation of toluene with $CrO_3$ in the presence of $(CH_3CO)_2O$ gives a product '$A$' which on treatment with aqueous $NaOH$ produces