State whether the following statements are True or False:
$(i)$ Compared to moist air,the speed of sound is greater in dry air.
$(ii)$ When the prongs of a tuning fork are rubbed,its frequency decreases.
$(iii)$ In the case of a stationary wave,the amplitudes of particles in any one loop are the same.
$(iv)$ In the case of a stationary wave,the amplitude of a particle decreases from node to antinode.

(D) $(i)$ False. The speed of sound in air is given by $v = \sqrt{\frac{\gamma P}{\rho}}$. Since moist air is less dense than dry air,the speed of sound is greater in moist air.
$(ii)$ False. Rubbing or filing the prongs of a tuning fork removes material,which decreases the mass of the prongs. According to the frequency formula $f \propto \frac{1}{\sqrt{m}}$,the frequency increases.
$(iii)$ False. In a stationary wave,the amplitude varies from zero at the nodes to a maximum at the antinodes. Particles in a loop have different amplitudes depending on their position.
$(iv)$ False. In a stationary wave,the amplitude of a particle increases from zero at a node to a maximum value at the antinode.