Solutions: NEET Notes and Important Questions by PW

Starting Class 12 Chemistry preparation requires a clear study routine, the right learning resources and regular question practice. For NEET aspirants, balancing board examinations with entrance exam preparation also means understanding NCERT concepts, practising previous year questions and revising topics consistently.

PW provides preparation planning, study habits, books and resources, and syllabus discussion before introducing the chapter Solutions. The online lessons cover the definition of a solution, identification of solute and solvent, types of solutions based on composition and concentration, and the classification of gaseous, liquid and solid solutions. Use these notes and worked questions to revise the key concepts from the class.

Solutions: Definition And Importance

Solutions is an important and examination-relevant chapter. The lecture indicates that students may expect approximately two questions in NEET 2027 from this chapter. For board examinations, it may carry around five marks on average, though exact weightage can differ by state board.

A solution is a homogeneous mixture of two or more chemically non-reactive substances.

Important features include:

• A solution is a mixture, not necessarily a chemical reaction.

• Its components remain chemically non-reactive.

• It has uniform composition and uniform properties throughout.

• Its particle size is approximately 1 nanometre or (10^{-9}) metre.

Every solution contains:

• One solvent

• One or more solutes

A solute is the substance that dissolves. A solvent is the substance in which dissolution occurs. In salt water, salt is the solute and water is the solvent.

Identifying Solute And Solvent

Components In Different Phases

When components are in different phases, identify the component that is in the same phase as the solution.

The component present in the same phase as the solution is called the solvent.

For example, if one component is solid and another is liquid:

• In a liquid solution, the liquid component is the solvent.

• In a solid solution, the solid component is the solvent.

Quantity is not considered first in different-phase systems.

Components In The Same Phase

When the components and the solution are in the same phase, the component present in the larger quantity is the solvent.

Compare quantity in this order:

1. Moles

2. Mass

3. Volume

The component in the smaller quantity is the solute.

(*Memory Tip: Different phases? Check the phase. Same phase? Check quantity. Compare quantity as Moles → Mass → Volume.)

Types Of Solutions By Number Of Components

• Binary Solution: One solute and one solvent; two total components.

• Ternary Solution: Two solutes and one solvent; three total components.

• Quaternary Solution: Three slutes and one solvent; four total components.

The course mainly focuses on binary solutions. In the conventional notation used in the lecture:

Solvent = 1; Solute = 2

Types Of Solutions By Concentration

A dilute solution contains a relatively smaller amount of solute in a given amount of solvent.

A concentrated solution contains a relatively greater amount of solute in a given amount of solvent.

These are relative terms. For the same amount of solvent, the solution containing more solute is more concentrated.

Types Of Solutions By Physical State

The physical state of a solution is determined by the physical state of its solvent:

• Solid solution: solid solvent

• Liquid solution: liquid solvent

• Gaseous solution: gaseous solvent

Gaseous Solutions

Liquid Solutions

An aqueous solution has water as its solvent. A non-aqueous solution uses another liquid, such as CCl₄ or benzene, as the solvent.

(*Memory Tip: Aqueous always means water is the solvent.)

Solid Solutions

Solid solutions include:

• Alloys: Solid in solid, such as brass and bronze

• Amalgams: Mercury dissolved in a metal

• Hydrogen gas adsorbed on a metal surface: gas in solid

In an amalgam:

• Metal is the solid solvent.

• Mercury is the liquid solute.

(*Memory Tip: Amalgam = Mercury dissolved in a metal.)

Important Questions on Solutions with Answers

Q1. What is a solution? State its main characteristics.

Answer: A solution is a homogeneous mixture of two or more chemically non-reactive substances.

Its main characteristics are:

• It has a uniform composition throughout.

• Its components are uniformly distributed.

• It is a mixture rather than necessarily a product of a chemical reaction.

• The particle size is approximately 1 nm or 10⁻⁹ m, as stated in the notes.

Q2. How can you identify the solute and solvent when the components are in different physical states?

Answer: When the components are in different phases, the component in the same physical state as the final solution is identified as the solvent.

For example, in a solid dissolved in a liquid to form a liquid solution, the liquid is the solvent and the solid is the solute.

Q3. A mixture contains 2 moles of component A and 5 moles of component B. Both components are in the same physical state as the final solution. Which component is the solvent?

Answer: When the components are in the same phase, compare their quantities.

Component A = 2 moles

Component B = 5 moles

Since component B is present in the greater number of moles, B is the solvent and A is the solute.

Q4. Differentiate between binary, ternary and quaternary solutions.

Answer:

• Binary solution: Contains two components, usually one solvent and one solute.

• Ternary solution: Contains three components, usually one solvent and two solutes.

• Quaternary solution: Contains four components, usually one solvent and three solutes.

The classification depends on the total number of components present in the solution.

Q5. What is the difference between a dilute solution and a concentrated solution?

Answer:

• A dilute solution contains a relatively smaller amount of solute for a given amount of solvent.

• A concentrated solution contains a relatively greater amount of solute for a given amount of solvent.

These terms are relative. A solution is more concentrated than another when it contains more solute for a comparable amount of solvent.

Q6. Classify the following solutions according to their physical states: air, sugar in water, brass and carbon dioxide in soft drinks.

Answer:

• Air: Gas dissolved in gas; a gaseous solution.

• Sugar in water: Solid dissolved in liquid; a liquid solution.

• Brass: Solid dissolved in solid; a solid solution or alloy.

• Carbon dioxide in soft drinks: Gas dissolved in liquid; a liquid solution.

The physical state of a solution is determined by the physical state of its solvent.

Q7. What are aqueous and non-aqueous solutions? Give one example of each.

Answer:

• Aqueous solution: A solution in which water is the solvent. Example: sugar in water.

• Non-aqueous solution: A solution in which a liquid other than water acts as the solvent. Examples include solutions using benzene or carbon tetrachloride (CCl₄) as the solvent.

Remember: aqueous always means that water is the solvent.

Watch Day 01 Chemistry Class for NEET 2027 by PW to learn how to prepare for board examinations and NEET, choose study resources, plan syllabus coverage and understand the chapter Solutions. The lecture also explains solute and solvent identification, types of solutions based on concentration and composition, physical states of solutions, and related questions.

The chapter Solutions introduces the basic concepts needed to understand mixtures and their classification in Physical Chemistry. Revise the definition of a solution, practise identifying solute and solvent, and learn the differences between binary, ternary and quaternary solutions.

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