Question 4
What is the balanced equation for heating potassium chlorate?
The right answer is the one marked above.
2KClO3 → 2KCl + 3O2. Both sides have two K, two Cl and six O.
Count the oxygens: 2 × 3 = 6 on the left and 3 × 2 = 6 on the right. Without the coefficient 2 the left has three oxygens, which cannot be divided into O2 molecules.