What is the coefficient of hydrogen in the balanced equation for the reaction between calcium and hydrogen?

The balanced equation for the reaction between calcium (Ca) and hydrogen (H₂) to form calcium hydride (CaH₂) is:

[ \text{Ca} + \text{H}_2 \rightarrow \text{CaH}_2 ]

In this reaction, the coefficient of hydrogen is 1, as one molecule of hydrogen gas (H₂) is required to produce one formula unit of calcium hydride (CaH₂).