What is the wavelength for a wave having frequency $50 \ Hz$?

The frequency of a wave of light is $12 \times 10^{14} \ s^{-1}$. The wave number associated with this light is

The energy of one mole of photons of radiation whose frequency is $5 \times 10^{10} \, s^{-1}$ is .......... $J$.

Given below are two statements about $X$-ray spectra of elements :
Statement $(I) :$ $A$ plot of $\sqrt{\nu}$ ($\nu =$ frequency of $X$-rays emitted) vs atomic mass is a straight line.
Statement $(II) :$ $A$ plot of $\nu$ ($\nu =$ frequency of $X$-rays emitted) vs atomic number is a straight line.
In the light of the above statements choose the correct answer from the options given below :

Splitting of spectral lines under the influence of a magnetic field is called:

While passing through an applied magnetic field,which of the following undergoes the maximum deflection?