they can work both on positive and negative supplies

they consist of both P-type and N-type semiconductor

the conduction of current through them is caused by both 'holes' and 'free electrons'.

of all the three above stated reasons

Germanium, rectifier

Silicon, rectifier

Germanium, signal detector

Silicon, signal detector

Avalanche effect

Hall effect

Breakdown effect

Seeback effect

is minimum when load current is zero

is maximum when load current is zero

is always zero

remains constant irrespective of load current variations

passes low frequency signals

passes high frequency signals

passes signals between two frequency limits

rejects signals between two frequency limits