Szczepan Bialek wrote:

napisa? w wiadomo?ci
...

Who wants to try to explain to this babbling idiot that the impedance of
a capacitor is 1 / ( 2 X pi X f X C) which means if f is zero (DC) the
impedance is infinite and there is no conduction (in an ideal capacitor).

You and teachers live in the ideal world where are the ideal capacitors.

I live in the real world and it is trivial to verify that the impedance
of a capacitor is 1 / ( 2 X pi X f X C).

As usual, you are totally confused.

Leyden jar has insulator made of glass.
It is possible to make it with insulator "made" of the air.

What will be leakage in such case?

Leakage and impedance are two separate things, idiot.