The number of g-atom of oxygen in 6.02 x 10²⁴ CO molecules is

One molecule of CO contains one oxygen atom.
$\therefore 6.02\times {10}^{24}\text{ molecules of }\mathrm{CO}\text{ contain }6.02\times {10}^{24} \mathrm{oxygen} \mathrm{atoms}.$
$6.02\times {10}^{23}\text{ atoms of oxygen }=1\mathrm{g}\text{-atom of oxygen }$
$\therefore 6.02\times {10}^{24}\text{ atoms of oxygen }=10 \mathrm{g}\text{-atom of oxygen.}$