Which of the following contains the maximum number of atoms?

10g of CaCO₃=$\frac{10}{100}=0.1\mathrm{mol}.=0.1\times 5\mathrm{N} \mathrm{atoms}=0.5\mathrm{N}$

4g of hydrogen = $\frac{4}{2}=2\mathrm{mol}=2\times 2\mathrm{N}=4\mathrm{N} \mathrm{atoms}.$

9g of NH₄NO₃ = $\frac{9}{80}=\frac{1}{9}\mathrm{mol}=\frac{1}{9}\times 9\mathrm{N}=\mathrm{N} \mathrm{atoms}.$

1.8g of C₆H₁₂O₆ = $\frac{1.8}{180}=0.01\mathrm{mol}=0.01\times 24\mathrm{N}=0.24\mathrm{N} \mathrm{atoms}$