Write the chemical equation when: Oxalic and reacts with concentrated `H_2SO_4`.

Explanation

Concentrated `H_2 SO_4` is a strong dehydrating agent. It dehydrates oxalic acid to a mixture of CO and `CO_2`, formic acid to CO and sugar to sugar charcoal.
`{:(COOH),(|),(COOH):} underset(Delta)overset("Conc." H_2 SO_4)to H_2 O underset("carbon monoxide")(CO) + underset("Carbon dioxide")(CO_2)`