12.Rate of disappearance of reactant is equal to

Explanation

The correct answer for what the rate of disappearance of a reactant is equal to is:(d) Both a and b (Rate of reaction and Rate of formation of product)Here's why the other options are incorrect:(a) Rate of reaction: While the rate of disappearance of a reactant is indeed one component of the overall rate of reaction, it doesn't fully capture the complete picture. The rate of reaction also includes the rate of formation of products.(b) Rate of formation of product: This option focuses only on the formation of products and ignores the depletion of reactants. In a closed system, the rate of disappearance of reactants must be equal to the rate of formation of products for the law of conservation of mass to hold true.(c) Energy released during reaction: The energy released during a reaction, also known as the heat of reaction, is related to the overall change in enthalpy but is not directly equivalent to the rate of disappearance of the reactant.