Answer:
d) It will be cut to a fourth of the original force.
Explanation:
The magnitude of the electrostatic force between the charged objects is

where
k is the Coulomb's constant
q1 and q2 are the charges of the two objects
r is the separation between the two objects
In this problem, the initial distance is doubled, so
r' = 2r
Therefore, the new electrostatic force will be

So, the force will be cut to 1/4 of the original value.
B 0.4 m should be correct if not it is A
Answer:
total number of electron in 1 litter is 3.34 ×
electron
Explanation:
given data
mass per mole = 18 g/mol
no of electron = 10
to find out
how many electron in 1 liter of water
solution
we know molecules per gram mole is 6.02 ×
molecules
no of moles is 1
so
total number of electron in water is = no of electron ×molecules per gram mole × no of moles
total number of electron in water is = 10 × 6.02 ×
× 1
total number of electron in water is = 6.02×
electron
and
we know
mass = density × volume ..........1
here we know density of water is 1000 kg/m
and volume = 1 litter = 1 ×
m³
mass of 1 litter = 1000 × 1 × 
mass = 1000 g
so
total number of electron in 1 litter = mass of 1 litter × 
total number of electron in 1 litter = 1000 × 
total number of electron in 1 litter is 3.34 ×
electron
1 m = 1 000 000 ym
converted other way we can say that:
1 ym =

m
Now, since we have ym^2 which is ym*ym which means:
1 ym^2 =

m
we have 1,5 ym^2 which means that answer is: