Bonds between atoms break and new ones form and energy is either given out or taken in
Answer:
Force of attraction = 35.96
N
Explanation:
Given: charge on anion = -2
Charge on cation = +2
Distance = 1 nm =
m
To calculate: Force of attraction.
Solution: The force of attraction is calculated by using equation,
---(1)
where, q represents the charge and the subscripts 1 and 2 represents cation and anion.
k = 
F = force of attraction
r = distance between ions.
Substituting all the values in the equation (1) the equation becomes

Force of attraction = 35.96
N
I think it is "Known".
Radioactive decay is measured using a formula where the half-life <span>of an isotope is the time it takes for the original nuclei to decay half of its original amount.</span>