Here's how to write the balanced chemical equation for the decomposition of mercury(II) oxide:

Unbalanced Equation:

HgO → Hg + O₂

Balanced Equation:

2HgO → 2Hg + O₂

Explanation:

* Reactant: Mercury(II) oxide (HgO)

* Products: Mercury (Hg) and oxygen gas (O₂)

Balancing the Equation:

1. Oxygen: There are 2 oxygen atoms on the product side (O₂) and only one on the reactant side (HgO). To balance, place a coefficient of 2 in front of HgO.

2. Mercury: Now we have two mercury atoms on the reactant side (2HgO) and one on the product side (Hg). Place a coefficient of 2 in front of Hg to balance.

The balanced equation now shows that two moles of mercury(II) oxide decompose to produce two moles of mercury and one mole of oxygen gas.