6. Substance through which current can flow without change in its composition is

called:

A. Semi-conductor

B. Insulator

C. Resistor

D. Conductor

D. Conductor

Explanation:

Conductors are the substances which are good conductors of both heat and electricity. These substances have free electrons present around the nucleus which is the main reason for conduction. Metals like copper, gold, silver, iron and steel etc are the examples of conductor. Gold is best conductor but cannot be used due to high cost. After gold, copper is the best conductor so that's why it is used extensively in electric wires.