In the given chemical equation, What is the missing coefficient to balance the equation?2 H2 + O2 → ___  H2O

The missing coefficient to balance the equation is 2. So, the balanced equation is: 2 H2 + O2 → 2 H2O.

Here's the step by step process:

1. Identify the type and number of atoms on both sides of the equation. In this case, we have 4 hydrogen atoms and 2 oxygen atoms on the left side, and 2 hydrogen atoms and 1 oxygen atom on the right side.

2. To balance the hydrogen atoms, we need to have the same number on both sides. Since we have 4 hydrogen atoms on the left side, we need to have 4 on the right side as well. To achieve this, we put a coefficient of 2 in front of H2O, which gives us 4 hydrogen atoms on the right side.

3. Now, we need to balance the oxygen atoms. We have 2 oxygen atoms on the left side and 2 on the right side (because of the coefficient of 2 in front of H2O), so the oxygen atoms are already balanced.

4. Therefore, the balanced equation is: 2 H2 + O2 → 2 H2O.