A laser produces monochromatic light of frequency $\nu = 6.0\times 10^{14}\,\text{Hz}$. The energy carried by each photon of this light is closest to which value? (Take $h = 6.63\times 10^{-34}\,\text{J\,s}$.)

1. A single photon carries energy $E = h\nu$. 2. Substitute $h = 6.63\times 10^{-34}\,\text{J\,s}$ and $\nu = 6.0\times 10^{14}\,\text{Hz}$. 3. $E = (6.63\times 10^{-34})(6.0\times 10^{14}) = 39.78\times 10^{-20} = 3.98\times 10^{-19}\,\text{J}$. 4. Rounded to two significant figures this is $4.0\times 10^{-19}\,\text{J}$. 5. Option A drops a factor; option C uses an incorrect Planck constant; option D doubles the energy, which is a common arithmetic slip. _Source: NCERT Class 12 Physics Part 2, Ch 11, Example 11.1, p. 10._