Answer : 2 represent the coefficient.
Explanation :
As we know that:
The coefficients used in the chemical equations shows that the relative amounts of each substance present and this amount can represent either the relative number of molecules or number of moles.
If there is no coefficient then one (1) is assumed.
That means,
The coefficient tell us about that how many molecules or atoms present in the chemical equation.
By the stoichiometry we have to convert moles of a reactant to moles of a product.
The given formula is:
In this formula, 2 represent the coefficient and 4 represent the subscript and C and H represents the symbol of element.
Hence, 2 represent the coefficient.