In the context of wave functions, what does the trough of a wave refer to?

If the amplitude of a wave is tripled, what happens to its frequency?

In the context of wave functions, what is the vertical distance between a trough and a crest called?

To change the frequency $f$ of a wave, which property of the wave must be altered?

Which of the following best describes the difference between $\mathrm{amplitude}$ and $\mathrm{wavelength}$ in a wave?

If the wavelength $\lambda$ of a wave increases while its speed $v$ remains constant, what happens to its frequency $f$?

Which of the following correctly defines the amplitude of a wave?

Which of the following best describes the medium through which seismic waves travel?

A wave is described by the equation $y=2\ast sin\left(4\pi t\right)$. What is the frequency of this wave?