Answer:
2
Step-by-step explanation:
Based on the chemical equation, the number of molecules of hydrogen gas in the reactant side is 2.
This is indicated by the coefficient before reactant.
A molecule is a covalent compound that has discrete or separate units.
So Hâ‚‚ is made up of two atoms of hydrogen that has been covalently bonded together by sharing their valence electrons.
From the reaction expression:
2 molecules of hydrogen gas combines with 1 molecule of oxygen gas to produce 2 molecules of water.