Given
The object has charge,
[tex]-2.4\times10^{-17\text{ }}C[/tex]To find
The number of excess electron
Explanation
The charge of a electron is
[tex]1.6\times10^{-19}C[/tex]Thus nuumber of electrons
[tex]2.4\times10^{-17}\frac{1}{1.6\times10^{-19}}=150[/tex]Conclusion
The number of electrons are 150