Question

One mole of any substance contains $6.022\times {10}^{23}$ atoms/molecules. Number of molecules of $H_{2}S{O}_4$ present in 100 mL of 0.02M $H_{2}S{O}_4$ solution is ___.

• A. $12.044\times {10}^{20}$ molecules
• B. $1\times {10}^{23}$ molecules
• C. $12.044\times {10}^{23}$ molecules
• D. $6.022\times {10}^{23}$ molecules

Answer 1

The correct option is A $12.044\times {10}^{20}$ molecules

Calculating the number of moles of $H_{2}S{O}_4$

Given:

1 mole of substance contains $6.022\times {10}^{23}$ molecules.

Volume of solution = 100 mL = 0.1 L
Molarity of solution = 0.02 M

We Know,

$Molarity=\frac{\text{number of moles of solute}}{\text{Volume of solution (in L)}}$

$\therefore$ no. of moles of solute = molarity $\times$ volume
$=0.02mol{L}^{-1}\times 0.1L$
= 0.002 mol

Calculating the number of molecules of $H_{2}S{O}_4$

Number of molecules of $H_{2}S{O}_4$
= number of moles $\times 6.022\times {10}^{23}$
=$0.002\times 6.022\times {10}^{23}$
= $12.044\times {10}^{20}$ molecules

Thus, $12.044\times {10}^{20}$ molecules of $H_{2}S{O}_4$ are present in 100 mL of 0.02 M $H_{2}S{O}_4$ solution.