Benzaldehyde reacts with ammonia to form

Number of products in the given reaction:
$C_6H_5CHO + CH_3CHO \xrightarrow{OH^-} \text{Product}$
will be

The end product $(B)$ of the above reaction is:

Identify the reagents $(1-4)$ required for the transformations shown and arrange them in the correct order.
$(1)$ $LiAlH_4$
$(2)$ $OsO_4$
$(3)$ $NaIO_4$
$(4)$ $NaBH_4$

In the following reaction sequence, the amount of $D$ (in $g$) formed from $10$ moles of acetophenone is. . . . . . (Atomic weights in $g \ mol^{-1}: H = 1, C = 12, N = 14, O = 16, Br = 80$. The yield (%) corresponding to the product in each step is given in the parenthesis)

When acetaldehyde is heated with Fehling solution,it gives a red precipitate of: