Question

Volume of a gas at $STP$ is $1.12\times 10^{-7}cc$. Calculate the number of molecules in it

• A. $3.01\times 10^{20}$
• B. $3.0\times 10^{12}$
• C. $3.01\times 10^{23}$
• D. $3.0\times 10^{24}$

Answer 1

Answer: (B)

$\therefore 22400cc$ of gas at $STP$ has $6\times 10^{23}$ molecules
$\therefore 1.12\times 10^{-7}$ of gas at $STP$ has $\frac{6\times 10^{23}\times 1.12\times 10^{-7}}{22400}$
$=3\times 10^{12}$