Between a photon of violet light with a wavelength of $4000 \ \mathop A\limits^o$ and a photon of red light with a wavelength of $7000 \ \mathop A\limits^o$,which one has higher energy?

Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength $8000 \ \mathring{A}$. What should be the maximum velocity of emitted electron when the same metal surface is exposed to radiation of wavelength $5000 \ \mathring{A}$? $\left( h = 6.6 \times 10^{-34} \ J \cdot s, \ m_e = 9.1 \times 10^{-31} \ kg, \ c = 3 \times 10^8 \ m/s \right)$

Wavenumber for a radiation having $5800 \ \mathring{A}$ wavelength is $x \times 10 \ cm^{-1}$. The value of $x$ is . . . . . . . .

Which of the following series of emission spectral lines for hydrogen is observed in the visible region?

Which of the following series correctly represents the energy of the radiation?

The momentum (in $kg \cdot m/s$) of a photon having $6 \, MeV$ energy is: