A sphere has a net charge of
![q=-4.8*10^(-17)\text{ C}](https://img.qammunity.org/2023/formulas/physics/college/k57vv3q0um8t1scjvg5cq81xdffn41r21i.png)
We have to find the number of excess electrons on the sphere.
By using the quantization of the charge as follows.
![q=ne](https://img.qammunity.org/2023/formulas/physics/college/oil03oh62csi9kjypi15m16a5nkv8ox16g.png)
Here, n is the number of excess electrons in the sphere.
And e is the charge of the electron calculated as
![e\text{ = 1.6}*10^(-19)\text{ C}](https://img.qammunity.org/2023/formulas/physics/college/hmb30ymewp9fvntropzs9sxv1mtae05rgx.png)
Now, the number of the excess electron in the sphere.
![\begin{gathered} n=(q)/(e) \\ n=\frac{-4.8*10^(-17)\text{ C}}{1.6*10^(-19)\text{ C}} \\ n=300 \end{gathered}](https://img.qammunity.org/2023/formulas/physics/college/os2r94bni9gne3skm96rqif11atsu0foz1.png)
So, there are 300 excess electrons on the sphere.