Question

$80\,g$ of oxygen contains as many atoms as in

• A. $80\,g$ of hydrogen
• B. $1\,g$ of hydrogen
• C. $10\,g$ of hydrogen
• D. $5\,g$ of hydrogen

Answer 1

Answer: (D)

$5\,g$ of hydrogen

Answer 2

Number of moles of oxygen $=\frac{80}{16}$

Number of atoms of oxygen $=\frac{80}{16} \times N_{0} \times 2$
$=5 \times N_{0} \times 2$

Number of moles of $5 \,g$ of hydrogen $=\frac{5}{1}$

Number of atoms in $5 \,g$ of hydrogen $=5 \times N_{0} \times 2$

Hence, the number of atoms in $80 \,g$ of oxygen is equal to the number of atoms in $5\, g$ of hydrogen.