Question

The energy of one mole of photons of radiation whose frequency is $3\times {10}^{12}Hz$ is:

• A. $1.9878\times {10}^{-21}J$
• B. $6.02\times {10}^{4}J$
• C. $1197.2J$
• D. $2394.4J$

Answer 1

The correct option is C $1197.2J$

Energy of a photon ; E = $h\nu$ ; where $\nu$ = frequency = $3\times {10}^{12}Hz$

Therefore energy = $6.6\times {10}^{-34}\times 3\times {10}^{12}Hz=1.9878\times {10}^{-21}J$

1 mole = $6.02\times {10}^{23}$ photons

Therefore energy of 1 mole of photons = $1.9878\times {10}^{-21}\times 6.02\times {10}^{23}=1197.2J$