Question

Find the odd one out of the following:
Copper, Salt water, Cotton, Human body.
(A) Human body
(B) Cotton
(C) Salt water
(D) Copper

Answer 1

In order to find which option is correct with respect to oddness of materials we should think these materials in relation of electricity such that those materials which allows the electricity to pass through them are known as conductors whereas materials which do not allow electricity to pass through them are known as insulators. We will examine each option one by one and will find out which one is odd among given materials.

Complete step by step answer:
First option is Human body. Since our human body consists of many ions in the form of potassium calcium sodium chloride and many other ions and these ions have a capability to conduct electricity and our body behaves as an electrolyte hence, Human body is a good conductor of electricity.
Second option is Cotton, since cotton is made of many linked fibres and in those fibres more air gets trapped in it and air itself is an insulator such that it makes cotton an insulator or poor conductor of electricity.
Salt water contains the ions of sodium and chloride because salt is composed of sodium and chlorine so, these ions conduct electricity and make saltwater a good conductor of electricity.
Copper has a very low resistivity and hence lower the resistivity higher the conductivity makes copper a good conductor of electricity.
So, among given options only cotton is an insulator and others are conductors of electricity.
Hence, the correct option is (B) Cotton.

Note:
It should be remembered that resistivity is the property of materials which is the measurement of resistance power of the material and tells about how strings a material can oppose the flow of current across it and conductivity is the measurement of strength of material which tells about how easily a material can allow electricity to pass through it.