Which of the following is dependent on the intensity of incident radiation in a photoelectric experiment

Specific heat of water is $4.2 \,J / g ^{\circ} C$. If light of frequency $3 \times 10^9 \,Hz$ is used to heat $400 \,gm$ of water from $20^{\circ} C$ to $40^{\circ} C$, the number of photons needed will be

If the two metals $A$ and $B$ are exposed to radiation of wavelength $350\,nm$. The work functions of metals $A$ and $B$ are $4.8\,eV$ and $2.2\,eV$. Then choose the correct option

Which of the following statement is not correct

Energy of a quanta of frequency ${10^{15}}Hz$ and $h = 6.6 \times {10^{ - 34}}J{\rm{ - }}\sec $ will be

$(i)$ In the explanation of photoelectric effect, we assume one photon of frequency v collides with an electron and transfers its energy. This leads to the equation for the maximum energy Emax of the emitted electron as $E_{max} = hf - \phi _0$ (where $\phi _0$ where do is the work function of the metal. If an electron absorbs $2$ photons (each of frequency $v$) what will be the maximum energy for the emitted electron ? 

$(ii)$ Why is this fact (two photon absorption) not taken into consideration in our discussion of the stopping potential ?