What are dielectric breakdown and dielectric strength?

A parallel plate capacitor with air as dielectric is charged by a $dc$ source to a potential $V,$ without disconnecting the capacitor from the source, air is replaced by another dielectric medium of dielectric constant $K.$ State with reasons how does

(i) Potential difference will be affected.

A parallel plate capacitor with air as dielectric is charged by a $dc$ source to a potential $V,$ without disconnecting the capacitor from the source, air is replaced by another dielectric medium of dielectric constant $K.$ State with reasons how does the electric field between the plates changes.

A parallel plate capacitor with air as dielectric is charged by a $dc$ source to a potential $V,$ without disconnecting the capacitor from the source, air is replaced by another dielectric medium of dielectric constant $K.$ State with reasons how does

capacity,

A parallel plate capacitor with air as dielectric is charged by a $dc$ source to a potential $V,$ without disconnecting the capacitor from the source, air is replaced by another dielectric medium of dielectric constant $K.$ State with reasons how does energy stored in the capacitor changed.

A parallel plate capacitor is charged by a battery. After some time, the battery is disconnected and a dielectric slab with its thickness equal to the plate separation is inserted between the plates. How will be The capacitance of the capacitor,

A parallel plate capacitor is charged by a battery. After some time, the battery is disconnected and a dielectric slab with its thickness equal to the plate separation is inserted between the plates. How will be the Potential difference between the plates

A parallel plate capacitor is charged by a battery. After some time, the battery is disconnected and a dielectric slab with its thickness equal to the plate separation is inserted between the plates. How will the energy stored in the capacitor be affected?