What is obtained when glycerol is heated with oxalic acid at $110\,^{\circ}C$?

Identify the product formed in the following reaction.
$C_6H_5-CH_2-CH_3 \xrightarrow[\text{ii) } H_3O^{+}]{\text{alk. } KMnO_4} \text{product}$

Toluene on reaction with reagent $A$ gives $X$. This $(X)$ forms $2,4-$dinitrophenylhydrazone and reduces ammonical silver nitrate solution. Reaction of toluene with another reagent $B$ forms $Y$,which dissolves in $NaHCO_3$ with evolution of $CO_2$. What are $A$ and $B$ respectively?

Identify the product formed in the following reaction.
$C_6H_5-CH_2-CH_3 \xrightarrow[ii) H_3O^{+}]{i) \text{alk. } KMnO_4} \text{Product}$

Malonic acid can be prepared from acetic acid using which combination of chemicals in the proper sequence?

What is the product of the following reaction?
$Hex-3-ynal$ $\xrightarrow[(ii) PBr_3]{(i) NaBH_4}$ $\xrightarrow[(ii) CO_2 / H_3O^{+}]{(i) Mg / ether}$ ?