Answer: Option (B) is the correct answer.
Explanation:
A substance which cannot be separated by any physical means or whose molecules are consistently distributed throughout the sample is known as a pure substance.
For example, gold, water, carbon dioxide etc are all pure substances.
Whereas a substance whose particles are microscopically and evenly distributed throughout a solution or mixture is known as a colloid. In a colloid particles are very small that they cannot be seen with a naked eye.
For example, milk is a colloid.
A mixture in which particles are not evenly distributed throughout and are not uniform in composition is known as a heterogeneous mixture.
For example, sand in water is a heterogeneous mixture.
A salt solution is a solution that contains different compounds like sodium, potassium, calcium etc that helps in maintaining pH and osmotic pressure in a body.
Thus, we can conclude that a mixture in which the suspended particles are too small to be seen with the naked eye is a colloid.
