Answer:
Burning of paper is not a physical change.It is chemical change as ash is formed in the process which is new compound and oxides of carbon are also released during the process!
Explanation:
Standard formation of an substance is defined as formation of one mole of substance from its constituting elements.
Chromium(III) nitrate is composed of chromium, nitrogen and three oxygen atoms.

A balanced chemical equation for the standard formation reaction of solid chromium(III) nitrate

It depends on the unit though if its in miles per hour then you can simply divide 50 by 2