Question

The volume of a gas in discharge tube is $1.12\times {10}^{-7}mL$ at $STP$. Then the number of molecules of gas in the tube is -

• A. $3.01\times {10}^4$
• B. $3.01\times {10}^{15}$
• C. $3.01\times {10}^{12}$
• D. $3.01\times {10}^{16}$

Answer 1

Answer: (C)

$3.01\times {10}^{12}$

As in $22400mL$ there is $1mol$,

So, number of moles in $1.1\times {10}^{-7}mL$, will have moles as follows:

Number of moles = $\frac{1.12\times {10}^{-7}}{22400}$

So, the number of molecules = $\frac{1.12\times {10}^{-7}}{22400}\times N_A=3.01\times {10}^{12}$

As $N_A=$ $6.022\times {10}^{23}$