What is the magnitude of the excess charge on the earth

Question

Compute all parts of following question given below:

Question: Earth has a net charge that produces an electric field of approximately 150 N/C downward at its surface.

Part I: What is the magnitude of the excess charge on the Earth, noting the electric field of a conducting sphere is equivalent to a point charge at its center in C?

Part II: What magnitude of acceleration will the field produce on a free electron near Earth's surface in m/s²?

Part III: What mass object with a single extra electron will have its weight supported by this field in kg?

I've been having quite a bit of trouble understanding this question, Thank you so much for your help. Thanks.