The answer for that would be C
Heat comes from the movement of molecules so it's B
true if you are refering to the desing of the experimnt as it does identify the variable
Answer:

Explanation:
Let the sphere is uniformly charge to radius "r" and due to this charged sphere the electric potential on its surface is given as

now we can say that


now electric potential is given as


now work done to bring a small charge from infinite to the surface of this sphere is given as


here we know that

now the total energy of the sphere is given as




Answer:
The current in the rods is 171.26 A.
Explanation:
Given that,
Length of rod = 0.85 m
Mass of rod = 0.073 kg
Distance 
The rods carry the same current in the same direction.
We need to calculate the current
I is the current through each of the wires then the force per unit length on each of them is
Using formula of force


Where, m = mass of rod
l = length of rod
Put the value into the formula




Hence, The current in the rods is 171.26 A.