Solutions

Correct answer: A. Air, salt in water, brass

The first example must be gaseous: air is a homogeneous mixture of gases and is classified as gas in gas. The second must be liquid: salt dissolved in water has liquid water as its solvent. The third must be solid: brass is a solid alloy and is classified as solid in solid. Therefore the sequence in option A exactly matches gaseous, liquid, and solid solutions.

Correct answer: A. Number of components is three

A ternary solution is one containing three components. Here the components are water, salt, and glucose, so the classification is based on component count. The mixture can still be homogeneous if both solutes dissolve uniformly. Ternary does not describe the physical state of the solvent or require a gaseous solute.

Correct answer: A. When states of solute and solvent are not checked

Colour is not the rule used to classify a solution. The classification depends mainly on the states of the solute and solvent, with the solvent determining the broad final state. If those states are ignored, a coloured or colourless sample can be misclassified. Homogeneity, water as solvent, or having two components does not itself cause this error.