Which of the following is an ohmic resistor?

1. LED
2. junction diode
3. filament of a bulb
4. nichrome wire

For which of the following substances, resistance decreases with increase in temperature?

1. copper
2. mercury
3. carbon
4. platinum

The properties for which nichrome wire is used in heating appliances is/are :

1. Specific resistance is high
2. Resistance decreases with an increase in temperature
3. Resistance increases with an increase in temperature
4. Both (1) and (3)

A super conductor is a substance of :

1. infinite conductance
2. infinite resistance
3. zero resistance
4. both (1) and (3)