A black body at 227^ C radiates heat at the rate of 7 cal cm^ -2...

Key Idea Apply Stefan's law of radiation. \begin{aligned} \mathrm{E} & =\sigma \mathrm{T}^4 \\ \frac{\mathrm{E}_1}{\mathrm{E}_2} & =\left[\frac{\mathrm{T}_1}{\mathrm{~T}_2}\right]^4 \\ \Rightarrow \quad \mathrm{E}_2 & =7\left[\frac{273+727}{273+227}\right]^4 \\ & =\left(\frac{1000}{500}\right)^4 \times 7 \\ & =112 \mathrm{cal}-\mathrm{cm}^{-2} \mathrm{~s}^{-1} \end{aligned}