1-a)What equal positive charges would have to be placed on Earth & on d moon to neutralize deir gravitational attraction?Do we need to know d lunar distances to solve this problem?Why or why not?
b)How many kilograms of Hydrogen would be neede to provide +ve charge on calculated in a)

2)Earth's atmosphere is constantly bombarded by cosmic rays protons that originate somewhere in space. If the protons all passed through the atmosphere each square metre of Earth's surface would intercept protons at the average rate of 1500 protons per second.What would be corresponding electirc current intercepted by the total surface area of the planet?

We do not have to know the distances because,
If we equate the forces, GMm/r^2=KQq/r^2, since r is same, it gets cancelled. Therefore, the product GMm= the product KQq.
Since the charges are equal,
we get
GMm=KQ^2, where M--> mass of earth, m--> mass of moon.
You know what G is.

One atom of H has one proton, which has a +ve charge of
magnitude 1.6x10^-19.
Therefore, no of H atoms = Q/Qp , where Q--> charge calculated in (a) and Qp --> 1.6x10^-19

mass of one H atom is known, and therefore we can find mass of that many atoms.