Question

Ordinary tap water conducts electric current due to:
A. The dissolved salts in it
B. Higher purity of the water
C. The bacteria present in it
D. None of these

Answer 1

Hint: Conduction of electricity in a fluid, in general, occurs by the movement of free ions in it. Hence, the availability of free ions in the fluid is a prerequisite for the conduction of electric current. Ionic compounds such as salts dissociate in water to form free ions.

Complete Step-by-Step solution:
A fluid conducts electricity in it by the passage of free ions in it. The free ions act as charge carriers and move under a potential difference, thus producing an electric current (since current is nothing but the quantity of charge passing per second in a conductor).
Free ions are formed generally, by the dissociation of the fluid (if it is an ionic one) or the ionic salts present in it. Ionic salts like sodium chloride, dissociate in a polar solvent like water. This produces free ions (cations and anions of the salt) in the liquid. These free ions help are responsible for the conduction of electricity.
Ordinary tap water contains many dissolved salts like chloride salts. These salts produce free ions and are the reason why ordinary tap water conducts electricity.
Hence, the correct option is A) the dissolved salts in it.

Note: Distilled water is extremely pure and thus, has no dissolved salts and hence, does not conduct electricity. Therefore, option B) is wrong since ordinary tap water is not pure and moreover, pure water does not conduct electricity.
The salts make ordinary water a good conductor of electricity. Rainwater has even more salts dissolved in it. This is the reason why after heavy rain and water logging, people can get electrocuted if a naked wire is exposed to a rainwater puddle and the man steps into it.