(a) List two differences between solids and liquids.

(b) The graph below is the heating curve for a solid X. Use the graph to answer Questions (i) — (iii) below.

(i) What is the melting point of X?

(ii) If the vapour of X is cooled, at what temperature will it start to condense?

(iii) (I) As X is heated, state what happens to the: I. frequency of collision of molecules of X;

(II) value of the entropy of the system.