Draw the structure of oxalic acid.

The major product obtained in the following reaction is:

The following transformation

can be carried out in three steps. The reagents required for these three steps in their correct order, are:

The major product of the following chemical reaction is :

What is $\mathrm{X}$?

In a set of the given reactions, acetic acid yielded a product C.

$\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}+\mathrm{P}\mathrm{C}{\mathrm{l}}_5\to \mathrm{A}$

$\mathrm{A}\underset{\mathrm{anhydrous}.\mathrm{ }{\mathrm{AlCl}}_3}{\stackrel{ {\mathrm{C}}_6{\mathrm{H}}_6 \mathrm{ }}{\to }}\mathrm{B}\underset{\mathrm{dry} \mathrm{ether}}{\stackrel{ {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{MgBr} \mathrm{ }}{\to }}\mathrm{C}$

Product C would be

How will you bring about the following conversion in not more than two steps? 

Benzoic acid to Benzaldehyde

 Complete each synthesis by giving missing starting material, reagent or products.