Solutions

The solvent is the component present in the larger amount and forms the continuous medium of a solution. Consequently, the solution generally has the physical state of its solvent: water gives a liquid solution, a gas gives a gaseous solution, and a solid metal can give a solid solution. Solute colour or impurities do not determine it.

To classify a solution, first identify whether the solute and solvent are solids, liquids or gases. Then identify the solvent and use its state to name the overall solution, such as solid in liquid or gas in liquid. Container colour and page number are irrelevant, and memorising names without checking states can cause errors.

An aqueous solution is specifically a solution in which water acts as the solvent. Salt dissolves in water and produces salt water, so this pair forms an aqueous solution. Copper-zinc is associated with an alloy, nitrogen-oxygen forms a gaseous mixture, and hydrogen in palladium is a gas-in-solid example rather than an aqueous solution.

The term aqueous means related to water. In solution terminology, any solution whose solvent is water is called an aqueous solution, whether the dissolved substance is a solid, liquid or gas. “Solid” and “gaseous” describe physical-state categories, while an alloy is a solid mixture of metals, so none of those terms defines a water-based solution.

Brass is an alloy in which solid metals are uniformly mixed at the material level. Since the solvent or major medium is solid and the whole alloy is solid at room temperature, brass is used as a standard example of a solid solution. Soda water, ethanol-water and oxygen in water have water as a liquid solvent.

Salt water is a liquid solution because solid salt is the solute and liquid water is the solvent. The solution is uniform and remains liquid at room temperature. Air is a gaseous solution, brass is a solid alloy, and copper mixed into gold represents a solid-in-solid solution. Therefore, salt water is the appropriate liquid-solution example.

Air is a uniform mixture of several gases, with nitrogen forming the largest proportion and other gases dissolved or mixed through it. Because the continuous medium and the solution as a whole are gaseous at room temperature, air is classified as a gaseous solution. Salt water and sugar water are liquid solutions, whereas brass is a solid solution.

The solvent forms the continuous phase and is usually present in the greater amount, so it controls the overall physical state of the solution. A solid dissolved in water still gives a liquid solution, while a gas dissolved in a solid metal gives a solid solution. A precipitate or impurity is not the general basis for classification.

The type is named by stating the solute first and the solvent medium second. Here the solute is a gas and the solvent is a liquid, so the correct description is gas in liquid. Carbon dioxide dissolved in water is a familiar example. The other choices reverse the states or use the wrong solvent state.

Brass is a homogeneous alloy made mainly by combining copper and zinc. Both metals are solids, and the resulting alloy is also solid at room temperature. In terms of the physical states of its components and medium, brass is therefore classified as a solid-in-solid solution. The other choices describe gas-liquid, liquid-gas or solid-liquid systems, not brass.

Glucose is a solid substance at room temperature, and water is a liquid solvent. When glucose dissolves uniformly in water, the physical-state combination is described as a solid solute in a liquid solvent, or a solid-in-liquid solution. The other choices incorrectly treat either the solute or the solvent as a gas or reverse their states.

Both water and ethanol are liquids at room temperature, and they mix uniformly with each other. In this mixture, one liquid acts as the solvent and the other as the solute, depending on their relative amounts; the state classification remains liquid-in-liquid. It is not a solid- or gas-based solution because neither component is a solid or gas under these conditions.

Hydrogen is the solute and is normally a gas, whereas palladium is a solid metal that acts as the solvent or host medium. Since the overall solution follows the state of its solid solvent, hydrogen dissolved in palladium is classified as a gas-in-solid or solid solution. Hydrogen itself does not become the solid solvent, and water is absent.

Mercury is a metal that is liquid at ordinary room temperature. An amalgam is formed when mercury combines with another metal, so identifying mercury supplies the liquid-component information needed for classifying the mixture. It is not a gaseous solute or an insoluble suspended particle; the exact overall class depends on which metal and which component is the solvent.

The overall state of a solution is generally determined by the solvent, which forms its continuous medium. Therefore, when the solvent is liquid and the solute dissolves uniformly, the mixture is called a liquid solution. The solute need not always be a gas; it may be a solid, liquid or gas. Insoluble components do not form a true solution.

A gaseous solution has a gas as its continuous medium, so its solvent is gaseous. The solute may be another gas and, in suitable examples, may be a liquid or solid substance dispersed at the molecular level. A solid solute alone does not make a gaseous solution, water gives an aqueous liquid solution, and heterogeneity contradicts the definition of a solution.

A solid solution is formed when the continuous medium or solvent is solid and the components are uniformly mixed. Alloys such as brass illustrate this idea. A gaseous mixture has a gas solvent, while sediment indicates that particles have not remained dissolved and uniformly distributed. Water as a solute does not by itself define a solid solution.

Brass is an alloy in which the component metals are solid and are uniformly mixed. One metal acts as the major solid solvent and the other as the solid solute, so brass is a solid-in-solid solution. Oxygenated water and soda water use liquid water as solvent, while air is a gaseous mixture; therefore those options do not meet the stated condition.

In hydrogen-in-palladium, hydrogen is the solute and palladium is the solid solvent or host metal. Because the continuous medium is solid, the overall solution is classified as a solid solution, specifically gas in solid. Salt, ethanol and oxygen in the other options are dissolved in liquid water, so those are liquid aqueous solutions.

Ethanol and water are both liquids at room temperature and are capable of mixing uniformly. In a mixture with one component in greater amount, that component is the solvent and the other is the liquid solute, giving a liquid-in-liquid solution. Air is gas in gas, brass is solid in solid, and camphor in nitrogen is solid in gas.

The phrase solid in liquid identifies a solid solute dissolved uniformly in a liquid solvent. Salt in water is a familiar example: salt is solid before dissolving and water is the liquid solvent. Option B describes gas in solid, option C describes gas in gas, and option D reverses the required solvent state, so they cannot define solid in liquid.

In a gas-in-gas solution, both the solute and the solvent are gases and they are uniformly mixed. Air is the standard example, with nitrogen as the major solvent and oxygen and other gases as solute components. A solid solvent describes a different class, and a gaseous solution is not automatically a suspension because suspension particles are not molecularly dissolved.

The solid substance is the solute and the liquid is the solvent. Uniform dissolution means that the particles are distributed throughout the liquid, producing a homogeneous solid-in-liquid solution. It is not heterogeneous because no separate solid phase remains visible, and it is not a pure substance because two substances are present. Solid in gas would require a gaseous solvent.

Here the gas is the solute and the solid metal is the solvent or host medium. Since the solvent is solid, the classification is gas in solid, and the overall material is treated as a solid solution. Gas in liquid would require a liquid solvent, gas in gas would require a gaseous solvent, and option B reverses the solute-solvent states.

Air is a gaseous solution because its major solvent is a gas. Salt water is a liquid solution because water is the liquid solvent, even though salt begins as a solid solute. Brass is a solid solution or alloy because its metallic components are solid. Therefore only option A gives the requested order: gaseous, liquid, solid.