Question

Which of the following charges is/are impossible?

• A. $4.8\times {10}^{-18}C$
• B. $5.8\times {10}^{-18}C$
• C. $12.8\times {10}^{-18}C$
• D. $20.8\times {10}^{-18}C$

Answer 1

The correct option is B $5.8\times {10}^{-18}C$

From $Q=ne$,
where $Q=$ total charge

$n=$ number of electrons

$e=$ charge on one electron

So, only that charge is possible for which charge is whole multiple of $1.6\times {10}^{-19}$ (i.e, charge on one electron).

We can see that multiplying $1.6\times {10}^{-19}$ with $30$ gives $A$

Multiplying $1.6\times {10}^{-19}$ with $80$ gives $C$

Multiplying $1.6\times {10}^{-19}$ with $130$ gives $D$

We can see that a, c and d are multiple of charge $1.6\times {10}^{-19}C$.

Only $5.8\times {10}^{-18}C$ given in B) option is not a multiple of $1.6\times {10}^{-19}C$.