please explain

5C
.
Energy released increases the temperature.
In the second case, the amount doubles – energy released doubles and mass heated doubles. The result temperature rise will remain the same.
.
Imagine the second situation as two sections – in each 5ml of A and B are reacting. The temp of each section rises by 5C as the first case tells us. The two section won’t exchange heat since the energy of both (c*m*dT) is the same.

thank you