Electrostatics ...

Assertion Annihilation of electron and positron is an example of decay of charges.
ReasonIn the process of annihilation an electron and a positron combine to give gamma ray.

Assertion Surface of a symmetrical conductor can be treated as equipotential surface.
ReasonCharges can easily flow in a conductor

Assertion The lightening conductor at the top of high building has sharp pointed ends.
Reason The surface density of charge at sharp points is very high resulting in setting up of electric wind.

Assertion A charged capacitor is disconnected from a battery. Now if its plate are separated farther, the potential energy will fall
Reason Energy stored in a capacitor is equal to the work done in charging it

Assertion The force with which one plate of a parallel plate capacitor is attracted towards the other plate is equal to square of surface density per co per unit area.
Reason The electric field due to one charged plate of the capacitor at the location of the other is equal to surface density per ɛ₀.

Assertion Mass of ion is slightly differed from its element.
Reason Ion is formed, when some electrons are removed or added so mass changes.

Assertion Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor does not change.
Reason The displacement current arises in the region in which the electric field and hence the electric flux does not change with time.

Assertion If a point q is placed in front of an infinite grounded conducting plane surface, the point charge will experience a force.
Reason This force is due to the induced charge on the conducting surface which is at zero potential.

Assertion The surface charge densities of two spherical conductors of different radii are equal. Then the electric field intensities near their surface are also equal.
Reason Surface charge density is equal to charge per unit area.

Assertion A bird perches on a high power line and nothing happens to the bird.
Reason The level of bird is very high from the ground.