Any change in the speed or direction of motion is called "acceleration". You'll hear "deceleration" used for slowing down but that's not technically correct.
Answer:
(a) 
(b) 
Explanation:
Parameter given:
Electric field, E = 
(a) Electric force is given (in terms of electric field) as a product of electric charge and electric field.
Mathematically:

Electric charge, q, of an electron = 

(b) This electrostatic force causes the electron to accelerate with an equivalent force:
F = -ma
where m = mass of an electron
a = acceleration of electron
(Note: the force is negative cos the direction of the force is opposite the direction of the electron)
Therefore:

Mass, m, of an electron = 
=> 
The acceleration of the electron is 
The correct answer is:
<span>Point charges must be in a vacuum.
In fact, the usual form for of the Coulomb's law is:
</span>

<span>where
</span>

is the permittivity of free space
<span>q1 and q2 are the two charges
q is the separation between the two charges
However, this formula is valid only if the charges are in vacuum. If they are in a material medium, the law is modified as follows:
</span>

where

is the relative permittivity, which takes into account the dielectric effects of the material.
While we think and feel that we are touching, we actually are not(: It’s all an illusion made by the brain
Because they are conducting, when you bring them together the charge is split equally among the two spheres (because they have the same radius the amount of charge is also equal). Now they will repel each other because of the net charge on each with the same polarity.