The subsurface zone in which all openings of the rock are filled with water is called the zone of saturation.
2.8 kg .............is the mass of a 1.2 N book.
The separation between them is 
Concept :
If the force increases, distance between charges must decrease. Force is indirectly proportional to the distance squared.
Given,
Two point charges are brought closer together, increasing the force between them by a factor of 20.
Original force is
F =
-------- ( 1 )
Here,
are charges and r is the distance between them
New force F' =
----------- (2 )
Divide ( 1 ) and ( 2 )
= 
20 = 
r' = 
Given that force between them are increasing and therefore distance between them decrease by 
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