Question

Hydrogen gas leaked out of a cylinder and only one gram of it was left. How many molecules are there in this one gram of hydrogen gas that is in constant random motion?

• A. $3.011\times {10}^{23}$
• B. $6.022\times {10}^{23}$
• C. $9.033\times {10}^{23}$
• D. $8.022\times {10}^{23}$

Answer 1

The correct option is A $3.011\times {10}^{23}$

Given mass of hydrogen = 1 g
Gram molecular mass of $H_2$ = 2 g

Number of moles of $H_2$ = $\frac{Givenmassingrams}{Grammolecularmass}$= $\frac{1}{2}$ = 0.5 moles

Number of molecules in 1 mol of substance = $6.022\times {10}^{23}$
So number of molecules in 0.50 mol of $H_2$
= $6.022\times {10}^{23}\times 0.5$
= $3.011\times {10}^{23}$