What is a coefficient? The number behind a chemical formula. The number in between the chemical symbols. The large number in front of a chemical formula. The small number on the right of the chemical symbol.

The correct answer is: The large number in front of a chemical formula.<br /><br />In chemistry, a coefficient is a number placed in front of a chemical formula to indicate the number of molecules or atoms of that substance involved in a chemical reaction. For example, in the chemical equation 2H2 + O2 → 2H2O, the coefficient 2 in front of H2 and H2O indicates that there are two molecules of hydrogen and two molecules of water involved in the reaction.