1: Types of Solutions

Correct answer: A. Components are uniformly mixed and every part of the sample is the same

Explanation: The defining macroscopic property of a true solution is homogeneity: every small portion has the same composition as every other portion. Its particles are sufficiently small that they do not form visible layers or settle under ordinary conditions. Separate layers and settling indicate a heterogeneous mixture, not a true solution. Therefore the uniform composition described in A is the correct identification criterion.

Correct answer: A. Both can be homogeneous solutions

Explanation: Air is a homogeneous mixture of gases, and brass is a homogeneous alloy of metals. In each case the components are uniformly distributed, so each can be treated as a solution in the broad chemistry classification. Their physical states are different and neither requires water as solvent. Also, their solutes are not necessarily liquid. Thus their valid similarity is homogeneous-solution character, making A correct.

Correct answer: A. Air is a gaseous solution whereas brass is a solid solution

Explanation: The physical class of a solution follows the state of its solvent. In air, the continuous medium is gaseous, mainly nitrogen, so air is a gaseous solution. In brass, the continuous medium is a solid metal, so brass is a solid solution. Neither is aqueous, because water is not the solvent. Therefore option A correctly states the main difference.

Correct answer: A. Gaseous solute: carbon dioxide in water

Explanation: Carbon dioxide is gaseous under ordinary conditions, and when it dissolves in water it acts as a gaseous solute in a liquid solution. Nitrogen in air is gaseous, water and alcohol are both liquids, and brass consists of solid metals. Thus options B, C, and D assign incorrect solute states. The correct state–example match is gaseous solute: carbon dioxide in water, so A is correct.

Correct answer: A. Solid solvent: brass

Explanation: Brass is a solid alloy, and its major component is treated as the solid solvent while the other metal is the solute. Salt water has liquid water as its solvent, air has a gaseous solvent because it is a gas mixture, and soda water also has liquid water as its solvent. Therefore, only the pairing “solid solvent: brass” is correct.

Correct answer: C. In a liquid solution, the solute is always solid

Explanation: A liquid solution is defined by its liquid solvent, not by a fixed state of the solute. The solute may be a solid, as in salt water; a liquid, as in alcohol mixed with water; or a gas, as in carbon dioxide dissolved in water. Soda water illustrates the last case. Therefore the claim that the solute is always solid is the incorrect idea, so C is correct.

Correct answer: C. Every solid solution has water as solvent

Explanation: A solid solution has a solid solvent, usually a solid metal or another solid matrix. Water is liquid at ordinary conditions and therefore is not the solvent in every solid solution. The solute may have a different state, as hydrogen gas in palladium demonstrates, and many alloys are solid solutions. Hence the universal statement that every solid solution has water as solvent is false. C is correct.

Correct answer: B. Brass

Explanation: Brass is a homogeneous solid alloy of metals. Its solvent is the major solid metal, not water, so it is a solid solution and also a non-aqueous solution. Salt water, soda water, and oxygen in water all use liquid water as solvent and are liquid solutions. Therefore brass alone satisfies homogeneity, non-water solvent, and solid overall state. B is correct.

Correct answer: A. Air, salt water, brass

Explanation: Air is a gaseous solution because its continuous medium is gaseous. Salt water is a liquid solution because water is its liquid solvent. Brass is a solid solution because its major metal component is solid. Thus the sequence in option A is gaseous, liquid, and solid. The other options place these examples in a different order or begin with a liquid solution, so they do not match the requested sequence.

Correct answer: B. The solute must be solid

Explanation: A liquid solvent makes the overall solution a liquid solution under the usual classification rule. However, the solute can have any of the three common states: a solid such as salt, a liquid such as alcohol, or a gas such as carbon dioxide. Therefore it is not always solid. Options C and D are valid possibilities, while B is the incorrect universal conclusion. Hence B is correct.

Correct answer: A. Air

Explanation: Air is a homogeneous mixture of gases. Nitrogen is the major component and acts as the solvent, while oxygen and other gases act as solutes. Since both the solvent and solutes are gases, the solution is classified as a gas-in-gas, or gaseous, solution. Ethanol in water and salt in water are liquid solutions, while brass is a solid solution.

Correct answer: A. Brass

Explanation: Brass is a homogeneous alloy mainly containing copper and zinc. Both components are present in the solid state, and copper generally acts as the solvent because it is present in larger proportion. Therefore brass is a solid-in-solid solution, commonly called a solid solution. Air is gaseous, whereas ethanol in water and soda water are liquid solutions.

Correct answer: A. The physical state of the solvent

Explanation: The broad physical-state category of a solution is identified mainly from the physical state of its solvent. A solid solvent generally gives a solid solution, a liquid solvent gives a liquid solution, and a gaseous solvent gives a gaseous solution. Colour, smell, and the length of a name do not determine this classification. Therefore, the solvent’s physical state is the relevant information.

Correct answer: A. Glucose in water

Explanation: An aqueous solution is a solution in which water acts as the solvent. In glucose dissolved in water, water is the continuous or solvent component and glucose is the solute, so the mixture is called an aqueous glucose solution. Air is mainly a gaseous solution, brass is a solid alloy, and camphor in nitrogen has nitrogen as solvent, not water. Hence option A is correct.

Correct answer: A. Ethanol in water

Explanation: Ethanol is a liquid and water is also a liquid. In the stated mixture, water is the solvent and ethanol is the liquid solute, so it represents liquid in liquid. Salt and glucose are normally solid solutes, while oxygen is a gaseous solute. All four may be aqueous if water is the solvent, but only option A has a liquid solute.

Correct answer: A. Oxygen in water

Explanation: Oxygen is a gas at ordinary conditions, and it can dissolve to some extent in water; for example, dissolved oxygen is present in natural water. In this case water is the liquid solvent and oxygen is the gaseous solute. Salt, glucose, and sugar are solid solutes when dissolved in water, so they do not satisfy the stated condition. Therefore option A is correct.

Correct answer: A. Salt in water

Explanation: In salt dissolved in water, water is the solvent and salt is the solute. Salt is a solid substance before dissolving, so this is an example of a solid solute in a liquid solvent, producing a liquid solution. Oxygen is a gaseous solute, ethanol is a liquid solute, and air does not represent water as solvent. Thus option A is the only suitable answer.

Correct answer: A. Final state is generally like solvent state

Explanation: In the usual classification of solutions, the physical state of the final solution follows the state of the solvent, which is the continuous medium. Thus a liquid solvent gives a liquid solution, even when the solute is solid or gaseous. The solute state, colour, and component count alone do not determine the broad final state.

Correct answer: A. Solid solution

Explanation: The broad physical category of a solution is named from the state of its solvent. Since the solvent in this question is solid, the homogeneous mixture is classified as a solid solution. The solute could be solid, liquid, or gas; that detail would specify the state combination, but it would not change the broad category determined by the solid solvent.

Correct answer: C. Gaseous solution

Explanation: A gaseous solvent forms the continuous phase of the mixture, so the broad solution category is gaseous solution. For example, air is a homogeneous mixture in which gases are dissolved or mixed in a gaseous medium. The fact that a solute might be liquid or solid does not by itself make the final solution liquid or solid; the solvent state controls the broad category.

Correct answer: A. Liquid solution

Explanation: A liquid solvent is the continuous phase, so the homogeneous mixture is broadly called a liquid solution. This remains true whether the solute is a solid, such as salt, a liquid, such as ethanol, or a gas, such as oxygen. The term alloy is restricted to suitable metallic mixtures and cannot describe every solution with a liquid solvent.

Correct answer: A. Final state is generally like solvent state

Explanation: The solvent forms the continuous phase and therefore generally determines the physical state used to classify the final solution. A liquid solvent gives a liquid solution even when the solute is solid or gaseous; a solid solvent gives a solid solution. The words “generally” and “broadly” are important because the rule describes classification, not every microscopic detail.

Correct answer: A. Salt in water

Explanation: In salt dissolved in water, salt is a solid solute, while water is a liquid solvent; the resulting homogeneous solution is liquid. Thus the solute and the solution have different physical states. In air, the gaseous solute and solution are gaseous. In ethanol-water and ordinary brass, the relevant components and the resulting solution are generally in the same liquid or solid state, respectively. Therefore A is correct.

Correct answer: A. This generally happens in every proper solution

Explanation: In the standard classification of solutions, the solvent is the continuous medium, so the final solution generally has the same broad physical state as the solvent. This applies to liquid solutions such as salt water, solid solutions such as brass, and gaseous solutions such as air. It is not restricted only to air or brass, and it is not never true.

Correct answer: A. Air is a homogeneous mixture of gases, so it is a gaseous solution

Explanation: Air contains several gases, including nitrogen, oxygen, argon, and small amounts of other gases, mixed approximately uniformly. Nitrogen is the major component and is commonly treated as the solvent; the other gases are solutes. Because the continuous medium is gaseous, air is a gaseous solution, not an aqueous solution, a solid-in-gas classification, or pure nitrogen.