Explanation:
It is given that r = 0.283 nm. As 1 nm =
.
Hence, 0.283 nm = 
- Formula for coulombic energy is as follows.

where, e =
C
= 

= 
- As 1 eV =

So, 1 J = 
Hence, U = 
= 8.9 eV
- Also, 1 J =

=
kJ/mol
Therefore, U =
kJ/mol
= 
Yes, it is true that ions can have a positive or negative charge.
Energy, Temperature, and Changes of State
Matter either loses or absorbs energy when it changes from one state to another. For example, when matter changes from a liquid to a solid, it loses energy. The opposite happens when matter changes from a solid to a liquid.
Add a coefficient 2 before H2O and a 2 before SO2.