Question

Find the total number of electrons present in 20 millimoles of $K_{2}S{O}_4.$

• A. $2.03\times {10}^{24}$
• B. $6.02\times {10}^{23}$
• C. $1.04\times {10}^{24}$
• D. $1.20\times {10}^{23}$

Answer 1

The correct option is C $1.04\times {10}^{24}$

Total number of electrons in one formula unit of $K_{2}S{O}_4=(19\times 2)+16+(8\times 4)=86$

So, the total number of electrons present in one mole of $K_{2}S{O}_4=86\times 6.022\times {10}^{23}$

Hence, the total number of electrons in 20 millimoles of $K_{2}S{O}_4$ are
$=20\times {10}^{-3}\times 86\times 6.022\times {10}^{23}=1.04\times {10}^{24}$