Newton's second law:

If there is no net force acting on an item, its velocity will remain constant. Either the thing is at rest with no velocity or it is moving in a straight line at a constant speed.

a)

Since a drop of rain falls at a constant speed, the rain's net force is zero.

a = \frac{dv}{dt} = 0

F_{net} = m* 0 = 0

b)

When a cork floats on water, it is subjected to two forces: the weight of the cork acting downwards and the buoyancy force acting upwards. Body floating means that upward force is balanced by downward force, according to Archimedes' principle.

F_{net} = 0

c)

Since the kite is stationary, the algebraic sum of forces acting on it is zero, according to Newton's second law

d)

Because the car is driving at a constant speed, the net force action on it is zero.

e)

Because the electron in free space is not subjected to electric, magnetic, or gravitational fields, the net force acting on it is zero.