- (T, F) In the decomposition of HgO, Hg and O 2 are the products. The
equation is 2HgO → 2Hg + O 2 (g)It is not always true that the number of atoms of each product is equal. It
happens in this reaction because there is an equal number of atoms of
Hg and O in the formula. In decomposing water you have: 2H 2 O →
2H 2 (g) + O 2 (g) because there are twice as many atoms of hydrogen than
oxygen in the original formula.