Which one of the following statements about mixtures is correct [2] [3] the different substances in a mixture are always in a definite proportion to cacho a mixture is made up of elements that are chemically combined it is extremely difficult to separate a mixture into different substances a mixture must contain at least two different substances a mixture is always homogeneous.

Option (4) is the correct answer.

Explanation:

A mixture is defined as a substance that contains two or more different substance that are physically mixed with each other.

If solute particles are evenly distributed in a solvent then it is known as a homogeneous mixture.

For example, salt dissolved in water is a homogeneous mixture.

If solute particles are unevenly distributed into the solvent then it is known as a heterogeneous mixture.

For example, sand in water is a heterogeneous mixture.

Thus, we can conclude that the statement a mixture must contain at least two different substances, is correct about mixtures.