Question

Which of the following contains the greatest total number of atoms?

• A. One mole of $C{O}_2$ (Molecular weight = $44$ g/mole)
• B. One mole of $H_2{O}_2$ (Molecular weight = $34$ g/mole)
• C. One molecule of $C_6{H}_{12}{O}_6$ (Molecular weight = $180$ g/mole)
• D. One gram of helium (Atomic weight = $4$ g/mole)
• E. One gram of $H_{2}O$ (Molecular weight = $18$ g/mole)

Answer 1

The correct option is B One mole of $H_2{O}_2$ (Molecular weight = $34$ g/mole)

• One mole of $C{O}_2$ contains $3N_A$ atoms
  
• One molecule of $H_2{O}_2$ contains 4 atoms. So, one mole of $H_2{O}_2$ contains $4N_A$ atoms,
  
• One molecule of glucose $C_6{H}_{12}{O}_6$ contains $24$ atoms.
  
• One gram of helium (atomic weight = 4) corresponds to $\frac{1}{4}=0.25$ moles of $He$. $He$ is monoatomic gas. Hence, one gram of helium contains $0.25N_A$ atoms.
  
• One gram of $H_{2}O$ (molecular weight = 18) corresponds to $\frac{1}{18}=0.0555$ moles. One water molecule contains 3 atoms. Hence, one gram of $H_{2}O$ contains $3\times 0.0555\times N_A=0.167N_A$ atoms.

Therefore , one mole of $H_2{O}_2$ contains the greatest total number of atoms.