Solutions

A solution is generally described by the physical state of its solvent. In salt water, salt is the solute and water is the solvent. Because water remains a liquid and dissolves the salt uniformly, the mixture is called a liquid solution. Salt itself is solid, and the remaining choices contradict the definitions of solution and solvent. Therefore A is correct.

A gaseous solution has a gas as its solvent and is a uniform mixture of gases. Air is such a mixture: nitrogen is the major component and oxygen and other gases are mixed throughout it. Salt water and sugar water have liquid water as solvent, while brass is a solid alloy. Hence air is the correct example.

A solution is called liquid when its solvent is liquid. In salt water, water is the liquid solvent and salt is the dissolved solute, so it is a liquid solution. Brass is a solid-solid alloy, air is a gas-gas solution, and hydrogen in palladium is a gas-in-solid solution. Therefore option C is the only correct example.

A solid solution has a solid solvent and a uniform solid mixture is formed. Brass is an alloy of metals, mainly copper and zinc, whose components are solid in the alloy. Air is gaseous, soda water contains a gas dissolved in liquid water, and oxygenated water is also a gas-in-liquid example. Therefore brass is correct.

Copper and gold are both solid metals under ordinary conditions. If copper is distributed uniformly in gold, gold can act as the solid solvent and copper as the solid solute; the result is described as a solid-in-solid solution or alloy. Carbon dioxide and oxygen in water are gas-in-liquid examples, while the last option does not contain two solid components.

In salt water, salt starts as a solid and is the substance that dissolves, so it is the solute. Water is liquid and provides the dissolving medium, so it is the solvent. Air contains gases, brass has solid metallic components, and water in soda water remains liquid. Thus only option B correctly identifies both substances and their states.

The broad name of a solution—gaseous, liquid or solid—is generally based on the physical state of its solvent. After identifying the solvent, the state of the solute can be used to write the detailed form, such as solid in liquid. Container shape, colour and an assumed zero temperature do not determine this classification.

Air is a homogeneous mixture in which the solvent and the dissolved components are gases. Therefore it is classified as gas in gas. Brass is a solid alloy, salt water is solid salt in liquid water, and soda water is mainly carbon dioxide gas in liquid water. These state comparisons make option A the only correct pair.

Solution types are usually written as solute in solvent. The question gives a gaseous solute and a solid solvent, so the correct name is gas in solid solution. The remaining options either make the solute solid or liquid, or make the solvent gaseous. Identifying the state of each component before reading the options prevents reversing the order.

Air is a homogeneous mixture made mainly of nitrogen, oxygen and small amounts of other gases. The solvent and the solutes are therefore gases, so air is called a gas-in-gas solution. It is not gas in liquid because ordinary air is not a liquid medium, and it does not consist of solid solute particles.

Sugar is a solid solute, while water is a liquid solvent. When sugar dissolves, its particles spread throughout the water and form a uniform mixture. Thus the solution is classified as solid in liquid. It is not liquid in liquid because sugar is not a liquid, and it is not a gas or solid in solid solution because the solvent is water.

Carbon dioxide is a gas, and soda water is a liquid medium containing that gas in dissolved form. Therefore the combination is described as gas in liquid solution. The phrase begins with the solute, carbon dioxide, and ends with the solvent, water. The other choices incorrectly change the state of the solute or describe a different type of dissolved substance.

Brass is a homogeneous alloy made mainly from copper and zinc. Both components are metals that form a solid phase in the alloy; one can be treated as the solid solvent and the other as the solid solute. Hence brass is a solid-in-solid solution. The other choices involve a liquid or gas solute, or a liquid solvent, none of which describes ordinary brass.

A true solution is a homogeneous mixture, meaning its solute particles are distributed uniformly throughout the solvent. Every small portion has essentially the same composition. Solutions may involve solids, liquids or gases, and every solution has a solvent and at least one solute. Therefore the statements saying always heterogeneous, only solid, or no solvent are incorrect.

The word binary means composed of two parts. Therefore a binary solution has two components in total, commonly one solute and one solvent. The term does not mean two solutes or two solvents; it refers to the total number of components. Solutions with three or more components are not binary, and a one-component system is not a solution mixture in this sense.

The classification states the solute first and the solvent second. Since both substances in the question are liquids, the correct description is liquid in liquid solution. For example, alcohol mixed uniformly with water fits this category. Options B and C change the solute state, while D changes the solvent to a solid, so none of them matches the given conditions.

Vinegar is mainly a solution of acetic acid, a liquid, in water, another liquid. Since the solute and solvent are both liquids, its simple state-based classification is liquid in liquid. It is not classified here as solid in liquid, gas in liquid, or solid in solid. The word “mainly” allows the question to focus on the principal components rather than trace substances.

Glucose is a solid substance and water is a liquid solvent. When glucose dissolves, it forms a uniform solid-in-liquid solution. Oxygen in air is a gas-in-gas example, brass is a solid-in-solid alloy, and carbon dioxide in water is a gas-in-liquid solution. Comparing the physical state of the solute and solvent makes option A the only correct answer.

Oxygen is a gas and water is a liquid. When oxygen dissolves in water, the mixture is classified as gas in liquid; dissolved oxygen is important for aquatic organisms. Sugar in water is solid in liquid, copper and zinc form a solid-metal mixture, and dust in air is generally a suspension rather than a true solution.

A gaseous solution is one in which the solvent is a gas, and other gaseous components may be dissolved or mixed in it. Air is a familiar example because nitrogen is the major gaseous component. A solid solution has a solid solvent, a liquid solution has a liquid solvent, and an aqueous solution specifically has water as solvent. Therefore only A fits.

A solution with a liquid solvent is called a liquid solution. Salt water, sugar water and vinegar are common examples because water or another liquid provides the continuous dissolving medium. The terms solid and gaseous solution refer to solid and gaseous solvents, respectively. ‘Non-metallic’ is not a physical-state category.

When the solvent is solid, the solution is classified as a solid solution. Alloys such as brass are common examples because one solid metal forms the main medium and another component is distributed through it. A liquid solution has a liquid solvent, a gaseous solution a gaseous solvent, and aqueous means water is the solvent.

In a true solution, solute particles are extremely small and spread uniformly throughout the solvent. They do not settle at the bottom or float at the top under ordinary conditions, and they cannot be seen as large separate groups. This uniform distribution is why every portion of a solution has nearly the same composition.

Miscible liquids mix completely in all proportions and form a uniform liquid mixture. Since both the solute and solvent are liquids, the solution is classified as liquid in liquid. Water and ethanol are a familiar example. The other options require a solid or gas as one of the components, which does not match the condition given.

Brass is a solid alloy, so its major metallic component can act as a solid solvent and the other metal as a solid solute. Salt water and sugar water have liquid water as the solvent. In soda water, water is also the liquid solvent and carbon dioxide is the dissolved gas. Thus brass is the only example with a solid solvent.