They are compared by there size if thats what your asking.
Answer:
247.4
Step-by-step explanation:
- you can either use pi*diameter or 2pi*radius
- 
Answer:
The total charge on atom is -2.
Step-by-step explanation:
We are given the following in the question:
Electrons have a negative charge.
Let this charge be represented by -1.
Protons have a positive charge. Let this charge be represented by +1.
An atom have 2 more electrons than protons.
Let
be the number of protons.
Then, the number of electrons are 
Total charge on atom =
=Charge on atom = Charge of protons + Charge of electrons

Thus, the total charge on atom is -2.
When dividing decimals, you move them over until the denominator is a whole number, so 0.2 to 2. The divisor's decimal is also moved over, so 24.2 to 242.
Now we have 242/2. I think you can take it from there.