Question

what happens when nitric acid reacts with formalin

Answer 1

The reaction of both formaldehydeand formic acid with nitric acid (2–20N) has been studied at 100°. ... Nitrites do not react with formaldehyde in neutral solution, but nitrous acid, liberated by hot acid, decomposes partially into nitric acidwhich then reacts with formaldehydeas above.

Answer 2

liberated by hot acid , decomposes partially into nitric acid which then reacts with formaldehyde
the reaction of nitric acid (2-20N) with both formaldehyde and formic acid at 100"