The answer is group 18.
Explanation:
Group 18 is known as the Noble Gases. They are the most stable elements because they have a full outer shell of valence electrons, so they have no need to bond with other elements.
Given that,
Mass of each washer = 4.9 g
We need to calculate the mass of two washers in kg
Using conversion of unit
Mass of each washer 
So, Mass of two washers is

Put the value of m


If 4 washer are attached to the spring
We need to calculate the applied force on the car
Using formula of force

Put the value into the formula


Hence, (i), The mass of two washers is 0.0098 kg.
(ii). The applied force on the car is 0.192 N.
Electric field is defined as force per unit charge.
So it is given by

now we can find electric field by



So field strength is 0.75 N/C.
Answer: 2000 v/m, from B to A.
Explanation: if point A is at the origin (x=0m) and point B is at the point x= 0.150m, the distance between both points (d) = 0.150 - 0 = 0.150m
Point A is at a 200v potential and point B is at a potential of 500v.
Difference in potential produces a voltage (v) = 500 - 200 = 300v.
The relationship between voltage, electric field intensity and distance is given by the formulae below
v=Ed
Where v = voltage = 300v, electric field =?, d = 0.150m
300 = E×0.150
E = 300/0.150
E = 2000 v/m.
Since point B is at higher potential than A, it implies that if there is an electron in this field, it will move from B to A thus making the direction of field be from B to A.