18 gms of glucose contains

18 gram molecules = $\frac{18}{180}moles=0.1 mole$

1 molecule  ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6= 6 \mathrm{atoms} \mathrm{of} \mathrm{carbons}$

= 12 atoms of hydrogen

 = 6 atoms of oxygen

0.1 mole ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6=0.6$gram atom of carbon

= 1.2 gram atom of hydrogen

= 0.6 gram atom of oxygen

$=0.6 \mathrm{moles} \mathrm{of} {\mathrm{CO}}_2$