The energy of one quantum of $12-\mathrm{GHz}$ microwave radiation is (a) $8.0 \times 10^{-22} \mathrm{~J} ;$ (b) $4.0 \times 10^{-23} \mathrm{~J}$; (c) $4.0 \times 10^{-24} \mathrm{~J}$; (d) $8.0 \times 10^{-24} \mathrm{~J}$.

A blackbody heated to $900^{\circ} \mathrm{C}$ emits radiation at the rate of $850 \mathrm{~W}$. If the blackbody's temperature is increased to $1200^{\circ} \mathrm{C}$, the power becomes (a) $1130 \mathrm{~W}$; (b) $1340 \mathrm{~W}$; (c) $2110 \mathrm{~W}$; (d) $2700 \mathrm{~W}$.

Which has a higher temperature-a red-hot object or a white-hot one?

A blackbody radiates with median wavelength $2200 \mathrm{~nm}$. What's its temperature? (a) $975 \mathrm{~K}$; (b) $1050 \mathrm{~K}$; (c) $1850 \mathrm{~K}$; (d) $3020 \mathrm{~K}$.

How many hydrogen atoms are there in a $1-\mathrm{g}$ sample of pure hydrogen? (a) $6.0 \times 10^{23}$; (b) $6.0 \times 10^{24}$; (c) $6.0 \times 10^{25}$; (d) $6.0 \times 10^{26}$.