Question

The volume of neon gas in $c{m}^3$ at STP having the same number of atoms as that present in $800mg$ of $Ca$ is:
(At. mass : $Ca=40gmo{l}^{-1},Ne=20gmo{l}^{-1})$

• A. $56$
• B. $896$
• C. $224$
• D. $112$
• E. $448$

Answer 1

Answer: (E)

$448$

Mass of $Ca=800mg=\frac{800}{1000}=0.8g$

Moles of $Ca$ in $0.8g=\frac{0.8}{40}=2\times {10}^{-2}$

$\because$ At STP, volume of $1mole=22400c{m}^3$

$\therefore$ At STP, volume of $2\times {10}^{-2}moles$

$=22400\times 2\times {10}^{-2}=448c{m}^3$.