Solutions

Correct answer: A. Salt water

Salt water is an aqueous solution in which water is the medium that dissolves salt. Water is liquid under ordinary conditions, so it is a liquid solvent. Brass and other metallic alloys are solid solutions with solid metallic solvents, while air is a gaseous mixture whose main solvent is gaseous nitrogen. Therefore salt water is the correct example.

Correct answer: A. Air

Air is a homogeneous mixture of gases, with nitrogen present in the greatest amount and generally treated as the main solvent. Therefore its solvent is gaseous. Brass has a solid metallic solvent, while vinegar and sugar water have liquid solvents. The answer follows from identifying the physical state of the main component.

Correct answer: A. Liquid in solid solution

The naming order is solute state followed by solvent state. The solute here is liquid and the solvent is solid, so the correct description is liquid in solid. The phrase solid in liquid would reverse both roles, while the gas-based choices introduce a state not mentioned in the question.

Correct answer: A. Solid in solid solution

The name of a state-based solution gives the solute state first and the solvent state second. Both substances in the question are solids, so the solution is solid in solid. Alloys such as brass are familiar examples. Option B changes the solvent to a liquid, option C changes the solute to a liquid, and option D changes it to a gas, so none of those fits.

Correct answer: A. Gas in gas solution

The solute is named first and the solvent second in this classification. Since both the solute and solvent are gases, the correct type is gas in gas solution. Air is a common example of a uniform mixture of gases. Options B, C, and D incorrectly replace one of the stated components with a liquid or solid, so they do not match the question.

Correct answer: A. Homogeneous nature

The same taste in every portion indicates that salt particles are distributed uniformly throughout the water. Uniform composition is the defining feature of a homogeneous mixture and is characteristic of a solution. A heterogeneous mixture would vary from place to place, while no sediment or new colourless gas is described here.

Correct answer: A. Water and alcohol

Water and alcohol are both liquids and can mix uniformly, so one can act as the liquid solvent and the other as the liquid solute. Water and salt form a solid-in-liquid solution, while oxygen dissolved in water is gas in liquid. Copper and zinc are solid metals that can form a solid alloy. Therefore only water and alcohol fit liquid in liquid.

Correct answer: A. Sugar and water

Sugar is a solid and water is a liquid. When sugar dissolves in water, it forms a homogeneous solid-in-liquid solution. Oxygen in water is a gas-in-liquid example, water and alcohol are both liquids, and nitrogen with oxygen is a gas-gas mixture. Thus the states of the two substances identify sugar and water as the only correct pair.

Correct answer: A. Oxygen and nitrogen

Oxygen and nitrogen are both gases and can form a uniform gaseous mixture like the gaseous components of air. Sugar and salt with water are solid-in-liquid solutions, while copper and zinc are solid metals that can form a solid alloy. Since only A has two gaseous components, it is the correct choice.

Correct answer: A. Copper and zinc

Copper and zinc are both solid metals. When they are mixed uniformly, they can form a metallic alloy such as brass, which is classified as a solid-in-solid solution. Salt in water is solid in liquid, carbon dioxide in water is gas in liquid, and water with alcohol is liquid in liquid. Therefore copper and zinc are the correct pair.

Correct answer: A. State of the solvent

A solution is commonly classified as solid, liquid, or gaseous according to the physical state of its solvent, which forms the continuous medium. For example, water in salt solution is liquid, so the solution is liquid. Container shape, dissolving time, and colour brightness do not determine this classification.

Correct answer: A. Aqueous solution

A solution in which water acts as the solvent is called an aqueous solution. The word aqueous refers to water. For example, salt water and sugar water are aqueous solutions because salt or sugar dissolves in water. The terms solid solution, gaseous solution, and dry mixture do not specifically mean water-based solution.

Correct answer: A. Non-aqueous solution

When the solvent is not water, the solution is called a non-aqueous solution. For instance, iodine dissolved in alcohol has alcohol as its solvent and is non-aqueous. Non-aqueous describes the identity of the solvent; it does not mean that the solution must be gaseous or solid. Aqueous specifically requires water as solvent.

Correct answer: A. Water containing carbon dioxide

Carbon dioxide is a gas, while water is a liquid. When carbon dioxide dissolves in water, the gas acts as the solute and water acts as the solvent. Therefore, carbon dioxide in water is a gas-in-liquid solution. Sugar in water is solid in liquid, zinc-copper is a solid mixture, and air is mainly a gas-in-gas solution.

Correct answer: A. Water containing salt

In salt water, salt is the solute because it dissolves in another substance, and salt is solid before dissolving. Water is the solvent because it provides the liquid medium. Therefore, this is a solid-in-liquid solution. Oxygen in air is a gas-in-gas example, copper-zinc is a solid solution, and carbon dioxide in water is a gas-in-liquid solution.

Correct answer: A. Oxygen in air

Air is a homogeneous mixture of gases. In the usual school-level description, nitrogen, the major component, acts as the solvent, while oxygen and other gases are solutes. Thus, oxygen in air represents a gas-in-gas solution. Salt water and sugar water are solid-in-liquid solutions, while zinc in brass is a solid-in-solid solution.

Correct answer: A. Zinc in brass

Brass is a solid alloy mainly composed of copper and zinc. Both components are solids at ordinary conditions, and one is dispersed through the other in the solid state. Therefore, brass represents a solid-in-solid solution. Salt in water is solid in liquid, oxygen in water is gas in liquid, and nitrogen in air is gas in gas.

Correct answer: A. Uniform composition

A true solution is homogeneous, meaning its composition is uniform throughout the sample. Its solute particles are too small to be seen separately and do not settle on standing. Visible large particles, quick sediment formation, and separate layers are features of suspensions or heterogeneous mixtures, not true solutions.

Correct answer: A. Salt water

Salt water is a liquid solution because salt is dissolved uniformly in liquid water, and the solvent determines the physical state of the solution. Brass and a solid metal mixture are solid solutions or solid mixtures, whereas air is a gaseous solution. The visible state of the whole solution should be distinguished from the state of its solute.

Correct answer: A. Brass

Brass is an alloy mainly made by mixing copper and zinc in the solid state. The components are distributed uniformly throughout the solid material, so brass is treated as a solid solution. Soda water is gas in liquid, salt water is solid in liquid, and air is a gaseous solution. The state of the solvent is used to classify these examples.

Correct answer: A. Air

Air is a gaseous solution because it is a uniform mixture of gases. Nitrogen is the major component and is commonly treated as the solvent, while oxygen, carbon dioxide, and other gases act as solutes. Salt water is a solid-in-liquid solution, brass is a solid-in-solid solution, and vinegar is a liquid-in-liquid solution.

Correct answer: A. Identifying the states of solute and solvent

To classify a solution by physical type, first identify whether the solute and solvent are solids, liquids, or gases. Then describe the combination, such as solid in liquid or gas in liquid. Colour, smell, and container shape may vary without changing the solution type, so they cannot provide a reliable classification.

Correct answer: B. Physical states of solute and solvent

A solution type is identified by considering the physical states of its solute and solvent: solid, liquid, or gas. For example, sugar in water is solid in liquid, while air is gas in gas. Colour, smell, and container shape are not dependable criteria because they can change without changing the physical classification.

Correct answer: B. Gas in gas

Air is a homogeneous mixture containing gases such as nitrogen, oxygen, and small amounts of other gases. The components are gaseous, and the major component provides the gaseous medium. Therefore, air is classified as a gas-in-gas solution. The other options involve a solid or liquid solvent and do not describe ordinary air.

Correct answer: B. Solute

In soda water, carbon dioxide gas is dissolved in liquid water. The substance that dissolves is called the solute, so carbon dioxide is the solute and water is the solvent. It is not a solid impurity or a suspended particle because it is present in dissolved form rather than as visible, settling particles.