Assertion: We have a solid charged sphere. There are two points $P$ and $Q\text{.} P$ is a point lying between centre and surface of the sphere. $Q$ is at finite and non-zero distance from the surface outside the sphere. There will be no situation where electric potential is equal at $P$ and $Q$.

Reason: Rate of change of electric field with distance from centre merely represents, magnitude of electric potential at that point.

Assertion: Cyclotron is used to accelerate heavy charged particles, such as a proton. It is not suitable for accelerating light charged particles such as electrons.

Reason: Specific charge of a proton is more than compared to the electron.

Reason: Net electrostatic potential at the centre is zero. 

Assertion: Inside a solid charged sphere $E-r$ variation is linear.

Reason: Inside that solid charged sphere $V-r$ variation is parabolic.

Assertion: Two charges $+Q$ each are fixed at two points. If a third charge $+q$ is placed at centre, then this charge is in stable equilibrium condition line joining the charges.

Reason: Electrostatic potential energy of the system in this position is minimum.

Assertion: Two concentric spherical shells $A$ and $B$ are charged by charges $q_A$ and $q_B$. If $q_A$ is negative, then $V_A-V_B$ is also negative.

Reason: $V_A-V_B=\left(\frac{q_A}{4\pi {\epsilon }_0}\right)\left(\frac{1}{R_A}-\frac{1}{R_B}\right)$. Therefore, if $q_A$ is negative, then $V_A-V_B$ is also negative.

Assertion: Two identical balls are charged by $q$. They are suspended from a common point by two insulating threads $I$ each. In equilibrium, the angle between the threads is $180°$. (Ignore gravity)

Reason: In equilibrium tension in the springs is $T=\frac{1}{4\pi {\epsilon }_0}\frac{q·q}{l^2}$

Assertion: With the help of Gauss theorem, we can find electric field at any point.

Reason: Gauss theorem can be applied for any type of charge distribution.

Assertion: When a capacitor is charged by a battery half of the energy supplied by the battery is stored in the capacitor and the rest half is lost.

Reason: If resistance in the circuit is zero, then there will be no loss of energy.