Question

What quantities must be conserved in all chemical reactions?

Answer 1

`"Two quantities are CONSERVED absolutely:"`

`"(i) MASS; and (ii) CHARGE."`

Explanation:

See this [old answer.](https://socratic.org/questions/can-you-explain-balancing-chemical-equations-in-detail#365584) If you encounter a reaction where mass and charge are not explicitly conserved, then you know that the reaction is not in the race as a representation of physical reality.