Which parameter is indicated by the number of waves passing through a given point in one second?

Which of the following statements is $NOT$ true?

$750$ waves of an energy radiation pass in one minute from a point. What will be the wavelength of the radiation? (Assume the speed of radiation is $3 \times 10^8 \ m/s$)

What is the ratio of the energy of photons having wavelengths $2000 \ \mathring{A}$ and $4000 \ \mathring{A}$?

The ejection of the photoelectron from the silver metal in the photoelectric effect experiment can be stopped by applying a stopping potential of $0.35 \ V$ when radiation of $256.7 \ nm$ is used. Calculate the work function for silver metal.

What is the photoelectric effect? Explain it.