A gas molecule absorbs a photon of wavelength $400 \mathrm{nm}$ and releases two photons one of which has wavelength $800 \mathrm{nm}$. Find the wavelength of other photon.

The following graph represents the variation of photo current with anode potential for a metal surface. Here $I_1, I_2$ and $I_3$ represents intensities and ${\gamma }_1,{\gamma }_2,{\gamma }_3$ represents frequency for curves $1, 2$ and $3$ respectively, then

Given figure shows few data points in a photo-electric effect experiment for a certain metal. The minimum energy for ejection of electrons from its surface is: (Planck's constant $\mathrm{h}=6.62\times {10}^{–34}\text{ J.s}$)

The variation of the stopping potential $\left(V_{\circ }\right)$ with the frequency $\left(\nu \right)$ of the light incident on two different photosensitive surfaces M1 and M2 is shown in the figure. Identify the surface which has greater value of the work function.