The number of gram atom of oxygen in  $6.02\times {10}^{24}$ CO molecule is

One molecule of CO contains one oxygen atom

$\therefore 6.02\times {10}^{24}$ molecules of CO contain $6.02\times {10}^{24}$ oxygen atoms

$6.02\times {10}^{23}$ atoms of oxygen = 1 g - atom of oxygen

$\therefore 6.02\times {10}^{24}$ atoms of oxygen = 10 g - atom of oxygen