The correct option is (B) 2.186 × 10–3 (W / m2).
Explanation:
Intensity of radiation = I = {(power) / (area)} = (P/A) = {E / (A ∙ t)} and E = {(nhc) / λ}
hence I = {(nhc) / (λAt)}
∴ I = [{11 × 1011 × 6.625 × 10–34 × 3 × 108} / {10 × 10–10 × 0.01 × 10}] ---- λ = 10 Å = 10 × 10–10m, A = 0.01 m2 and t = 10 sec
∴ I = 218.6 × 10–5
∴ I = 2.186 × 10–3 (W / m2)