What is a thermochemical equation? Explain why is it essential to mention the physical states of reactants and products in thermochemical equations.

The correct thermochemical equation is :

Identify the correct state of reactants and products from the following equations :

When the solution of substance X is added to a solution of potassium iodide, then a a yellow solid separates out from the solution. (a) What do you think substance X is likely to be (b) Name the substance which the yellow solid consists of. (c ) Which characteristic of chemical reactions is illustrated by this example? (d) Write a balanced chemical equation for the reaction which takes place. Mention the physical states of all the reactants and products involved in the chemical equation.

Regarding a thermochemical equation a wrong statement is