Chemistry - Atomic Structure Question with Solution | TestHub

Light energy = $0.05\times 100W\times 7200s=3.6\times 10^4$ J.

Energy of one photon = $hc/\lambda =(6.626\times 10^{-34}\times 3\times 10^8)/(5.0\times 10^{-7})=3.98\times 10^{-19}$ J.

Number of photons = $3.6\times 10^4/3.98\times 10^{-19}=9.06\times 10^{22}$.

Trap: using the full 100 W gives $1.81\times 10^{24}$.

Answer: (C).