Mention A Change Which Is Always Desirable Undesirable And Periodic

Mention a change which is always desirable, undesirable and periodic.

Answers:

1. Desirable : Changes that are useful to man are desirable changes, e.g. change of milk into curd.
2. Undesirable : Change that brings about destruction is an undesirable change, e.g. floods and epidemics are undesirable changes.
3. Periodic : Changes that are repeated at regular intervals of time are called periodic changes, e.g. change of day and night.