# When the frequency of a sound wave is increased, which of the following decrease? (1)amplituted (2)period (3)wavelength

Firstly, frequency is defined as being the number of complete waves per second that pass a stationary object/point. Period is defined as the time for one full wave to pass, thus $f \left(H z\right) = \frac{1}{T \left(s\right)}$ So period will fall if frequency rises.
Secondly, the wave equation, $v = f \times \lambda$ so if v remains constant any increase in frequency must cause a reduction in wavelength. So wavelength decreases as frequency increases.