Question

Why do naphthalene balls disappear if kept for a few weeks

Answer 1

here is ur ans mate

napthlene balls are very reactive in nature they can disaapear in room temp becuase of their high reactiveness.

Answer 2

sublimation: sublimation is a process in which a solid particle directly changed into vapour state without changing into liquid state.e.g:napthalene balls, camphor etc...
here,
napthalene balls goes under sublimation process when kept in air for few weeks.it reacts with atmosphere and changes directly into it's vapour state from solid state as a result it disappears.
hope it's helpful !