Question

Poor conductors of electricity consist of:
A. Silver
B. Aluminum
C. Distilled water
D. Copper

Answer 1

Metals contain free electrons due to which they conduct electricity easily. Poor conductors or insulators contain very few or no free electrons.

Complete Step by Step Answer:
Electric current is the rate of flow of electrons per unit time.For conduction of current, free electrons or ions are essential. The conductivity of a substance increases with increase in ion concentration.

In an atom of a substance, the electrons in the orbits close to the nucleus are bound to it under the strong attraction of the nuclear positive charge, but electrons far from the nucleus experience a very feeble force. Hence, the outer electrons can be removed easily. In fact, the outer electrons leave their atoms and move freely within the substance. These electrons are called free electrons. In metals, the number of free electrons is quite very large. Hence, metals are good conductors of electricity. Silver is the best conductor of electricity, then are copper and aluminum respectively.

In liquids, electric conduction occurs by the movements of both positive and negative charge-carriers, ions. Usually water contains dissolved ions and impurities which makes it a good conductor of electricity. However, distilled water contains no dissolved salt or impurities in it, which can provide free ions for conduction of electricity. Hence, distilled water is a poor conductor of electricity. Therefore, option C is the correct answer.

Note: In any conductor, the direction of electric current is taken as the direction of flow of positive charge. As in metals only negative charge (electrons) flow. The direction of current is opposite to the direction of flow of electrons.