(i) Music is pleasant and relaxing when played at a moderate volume. However, when played loudly, it becomes noise, which causes stress, disturbs sleep and concentration, reduces efficiency, and invades people's peace and privacy. Hence, loud music is a source of noise pollution.
(ii) Secondary pollutants are formed by the chemical reactions of primary pollutants in the atmosphere. They react in the presence of sunlight, water vapour, or other chemicals to produce substances such as ozone and peroxyacetyl nitrate (PAN), which are often more toxic than the primary pollutants.
(iii) Pesticides are qualitative pollutants because they are synthetic toxic chemicals introduced into the environment by human activities. They degrade environmental quality by adding harmful substances that are not naturally present in the environment.