Which of the following statements is correct?

(A) Distilled water is a good conductor of electricity.

(B) An LED glows even when a weak electric current flows through it.

(C) Only liquid solutions of salts can conduct electricity.

(D) Zinc plating is done to make the object scratch proof.

(A) Distilled water is a good conductor of electricity. False

Distilled water is pure water devoid of mineral salts and cannot conduct electricity.

(B) An LED glows even when a weak electric current flows through it. True

An LED is generally used as a tester to detect the flow of weak electric current through it. It glows for a small variation in the voltage.

(C) Only liquid solutions of salts can conduct electricity. True

Salts need to disassociate into ions in order to conduct electricity. Hence, when salts are dissolved in water they can conduct electricity.

(D) Zinc plating is done to make the object scratch proof. True

Electroplating is the process of coating a metal over another metal in order to prevent rusting and also make the object scratch proof. Zinc metal is plated over iron in order to prevent rusting and makes it scratch proof.

Thanks & Regards,

Vasantha Sivaraj,

askIITians faculty

Hey there.. Distilled water is not a good conductor of electricity as it does not contain any ions to conduct the charges across it. Hence, distilled water is an insulator. A LED(Light Emitting Diode) is a heavily doped p-n junction which on forward biasing emits spontaneous radiations. When a weak electric current flows through a LED the intensity of the light produced is also low, and the intensity increases with current and reaches a maximum. Further increase in the forward current results in decrease in the intensity hence proper biasing is required. Yes, only liquid solutions of salts can conduct electricity as it contains free ions that help in the process of charge transfer leading to a flow of current through the solution. Yes, Zinc coating is done to make the object scratch proof. Moreover, it is done to prevent any other metal like iron from rusting. This process of coating a surface of metal with Zinc or other metals to protect it from physical changes is called as galvanization.