Answer:
a.Attractive

Explanation:
When it comes to charges, the charges which are alike repel each other and the charges which are different will attract each other.
Here, there is a proton and electron which are different particles hence, they will attract each other.
= Charge of electron and proton = 
r = Distance between them = 997 nm
k = Coulomb constant = 
Force is given by

The force of attraction between the particles will be 
What Newton discovered is that gravity extends throughout the universe.
<h3>What is gravity?</h3>
The term gravity refers to the force that acts on a body in the universe. It is gravity that makes an object to fall when it is thrown up. The force of gravity acts on every object in the universe and it extends through the universe.
Humans have always known about gravity when they fall from a height and when they threw things up. However, human did not know that gravity extends throughout the universe.
Thus, what Newton discovered is that gravity extends throughout the universe.
Learn more about gravity:brainly.com/question/4014727
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Answer:
weight = 25*10 =250 N
Explanation:
g must be given in units of m/s^2
The weight of any type of body will be the product of his mass by the gravity
where:
m =mass [kg]
F = force [N] or [kg*m/s^2]
g = acceleration [m/s^2]