In a bipolar junction transistor, select the incorrect statement.

Two identical $p\text{-}n$ junctions may be connected in series with a battery in three ways (figure below). The potential drops across the two $p\text{-}n$ junctions are equal in,

For the given circuit shown in figure, to act as a full wave rectifier, AC input should be connected across ___ and ___, the DC output would appear across ___ and ___.

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the,