How do u find which is physical or chemical changes

An exothermic reaction is conducted in an insulated calorimeter filled with water. the calorimeter is then sealed so that there is no heat exchanged between the contents of the container and the surrounding air. which of the following statements is true about the reaction?

Blank allows you to do calculations for situations in which only the amount of gas is constant a)boyle's law b)combined gas law c)ideal gas law d)dalton's law

Explanation for basic character?