Answer
(c), (e), and (f).
Work Step by Step
(a) Sugar does not change in composition when dissolves in water. (Physical)
(b) Boiling point is a physical property.
(c) Changes in composition (From $O_3$ to $O_2$). (Chemical)
(d) Density is a physical property.
(e) When sodium metal reacts with water, the following reaction happens:
$$Na_{(s)} + H_2O_{(l)} \longrightarrow NaOH_{(aq)} + \frac 12{H_{2}}_{(g)}$$
Therefore, there is a composition change. (Chemical)
(f) Combustion consists of a reaction with changes in compositions. (Chemical)
(g) Melting point is a physical property.
