Question

What is the number of molecules present in 0.5 mole of hydrogen?

• A. $3.011\times {10}^{22}$ molecules
  
• B. $3.011\times {10}^{23}$ molecules
  
• C. $3.011\times {10}^{20}$ molecules
  
• D. $6.022\times {10}^{23}$ molecules
  

Answer 1

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

From Avogadro's law, $1$ mole of any compound contains $6.022\times {10}^{23}$ molecules

$\therefore$ $1$ mole of $H_2$ contains $6.022\times {10}^{23}$ molecules of $H_2$

$\therefore$ $0.5$ mole of $H_2$ contains $=0.5\times 6.022\times {10}^{23}=3.011\times {10}^{23}$ molecules