What is the coefficient?
A. A whole number that appears in front of a compound or element in a balanced chemical equation.
B. A whole number that appears as a subscript in front of a formula in a balanced chemical equation
C. A whole number that appears as a subscript at the end of a formula in a balanced chemical equation.
D. A whole number that appears as a subscript at the end of a formula in a balanced chemical equation

A. A whole number that appears in front of a compound or element in a balanced chemical equation.  

Explanation:

That's the definition of a coefficient.

B, C, and D are wrong. Subscripts are not coefficients.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.

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