Thank you for reporting, we will resolve it shortly
Q.
The number of photons per second on an average emitted by the source of monochromatic light of wavelength $600\, nm$, when it delivers the power of $3.3 \times 10^{-3}$ watt will be : $\left( h =6.6 \times 10^{-34} Js \right)$
The number of protons delivered per second is given by
$\frac{ n }{ t }=\frac{ IA \lambda}{ hc }=\frac{ P \lambda}{ hc } $
$\Rightarrow \frac{ n }{ t }=\frac{3.3 \times 10^{-3} \times 600 \times 10^{-9}}{3 \times 10^{8} \times 6.6 \times 10^{-34}}$
$\frac{ n }{ t }=10^{16}$