Name the changes in the terms of processes P, Q, R and S. (b) Which of the changes are exothermic and endothermic?

(a) ‘P’ is fusion (melting), ‘Q’ is boiling, ‘R’ is condensation and ‘S’ is sublimation.

(b) ‘P’, ‘Q’ and ‘S’ are endothermic and ‘R’ is exothermic.