Question

Which one of the following statements is false for 0.5mol of $C_2{H}_6$? (C=12, H=1 and take Avogadro number = $6\times {10}^{23})$
A) It weights 15 g

B) It includes $3\times {10}^{23}$ $C_2{H}_6$ molecules

C) It includes 1mol C atom

D) It includes 4 atoms

• A. It is 15 g
• B. It includes molecules
• C. It includes 1mol C atom
• D. It includes 4 atoms

Answer 1

The correct option is D It includes 4 atoms

Molar mass of $C_2{H}_6=2.\left(12\right)+6.\left(1\right)=30\frac{g}{mol}$,

1mol $C_2{H}_6$ is $30\frac{g}{mol}$ $⟹$ 0.5mol $C_2{H}_6$ is = $\frac{15g}{mol}$. A is true.
1mol $C_2{H}_6$ includes $6\times {10}^{23}$ $C_2{H}_6$ molecule, 0.5 mol $C_2{H}_6$ includes:
$C_2{H}_6$ molecules = $3\times {10}^{23}$ $C_2{H}_6$ molecules, B is true.
1 mol $C_2{H}_6$ includes 2mol C atoms 0.5mol $C_2{H}_6$ include? Mol C atoms, C is true.
1mol $C_2{H}_6$ includes $8N_A$ atoms 0.5mol $C_2{H}_6$ includes = $4N_A$ atoms, D is false.