Question

Which of the following has the maximum number of moles?

• A. $7$gram of ${\mathrm{N}}_2$
• B. $2$gram of ${\mathrm{H}}_2$
• C. $8$gram of ${\mathrm{O}}_2$
• D. $20$gram of ${\mathrm{NO}}_2$

Answer 1

The correct option is B

$2$gram of ${\mathrm{H}}_2$

The explanation for the correct option

(B) $\mathbf{2}\mathbf{}$gram of ${\mathbf{H}}_{\mathbf{2}}$

• Mole of a substance is calculated by
• $\mathrm{No}.\mathrm{of}\mathrm{moles}=\frac{\mathrm{Molecular}\mathrm{weight}\left(\mathrm{M}\right)}{\mathrm{Given}\mathrm{weight}\left(\mathrm{W}\right)}$
• Molecular weight of ${\mathrm{H}}_2$$=2$
• Given weight$=2$
• Then, No. of moles of $2$gram of ${\mathrm{H}}_2$$=\frac{2}{2}$
• No. of moles of $2$gram of ${\mathrm{H}}_2$$=1\mathrm{mole}$
• It has a maximum number of moles.

Therefore, Option (B) $\mathbf{2}\mathbf{}$gram of ${\mathbf{H}}_{\mathbf{2}}$is correct.

The explanation for the Incorrect options

(A) $\mathbf{7}\mathbf{}$gram of ${\mathbf{N}}_{\mathbf{2}}$

• Molecular weight of ${\mathrm{N}}_2$$=28$
• Given weight$=7$
• Then, No. of moles of $7$gram of ${\mathrm{N}}_2$$=\frac{7}{28}$
• No. of moles of $7$gram of ${\mathrm{N}}_2$$=0.25\mathrm{moles}$

(C) $\mathbf{8}\mathbf{}$gram of ${\mathbf{O}}_{\mathbf{2}}$

• Molecular weight of ${\mathrm{O}}_2$$=32$
• Given weight$=8$
• Then, No. of moles of $8$gram of ${\mathrm{O}}_2$$=\frac{8}{32}$
• No. of moles of $8$gram of ${\mathrm{O}}_2$$=0.25\mathrm{moles}$

(D) $\mathbf{20}\mathbf{}$gram of ${\mathbf{NO}}_{\mathbf{2}}$

• Molecular weight of ${\mathrm{NO}}_2$$=46$
• Given weight$=20$
• Then, No. of moles of $20$gram of ${\mathrm{NO}}_2$$=\frac{20}{46}$
• No. of moles of $20$gram of ${\mathrm{NO}}_2$$=0.435\mathrm{moles}$

Therefore, Option (B) $\mathbf{2}\mathbf{}$gram of ${\mathbf{H}}_{\mathbf{2}}$is correct.