Practise Class 8 Science Chapter 9 – The Amazing World of Solutes, Solvents, and Solutions with this easy NCERT Curiosity worksheet. Includes important questions and revision exercises to strengthen understanding of solutes, solvents and solutions and prepare effectively for class tests and exams.
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Chapter 9 Worksheet
The Amazing World of Solutes, Solvents, and Solutions
Instructions:
- Read each question carefully.
- Show all steps in numerical questions.
- Use correct units wherever required.
- Try to answer the questions independently.
Section A – Multiple Choice Questions
1. Which substance is called the solute in a salt solution?
2. Which of the following is generally a good solvent?
3. A solution that cannot dissolve any more solute at a particular temperature is called:
4. Which instrument is commonly used to measure the volume of a liquid?
5. Which formula is used to calculate density?
6. Which one is generally less dense than water?
7. What usually happens to the solubility of most gases in water when temperature increases?
8. Which state of matter generally becomes less dense when heated?
Section B – Fill in the Blanks
1. The substance that dissolves in a solvent is called the .
2. The substance in which a solute dissolves is called the .
3. A solution that can dissolve more solute at a particular temperature is called an solution.
4. The maximum amount of solute that can dissolve in a given amount of solvent at a particular temperature is called its .
5. Density is equal to mass divided by .
6. One millilitre is equal to cubic centimetre.
7. Ice floats on water because ice is dense than liquid water.
8. The curved surface of a liquid in a measuring cylinder is called the .
Section C – True or False
1. Salt is the solvent in a salt-water solution.
2. A saturated solution cannot dissolve more solute at the same temperature.
3. Density depends on both mass and volume.
4. Oil sinks below water because oil is denser than water.
5. Gases are able to dissolve in liquids.
6. Heating generally decreases the volume of a substance.
Section D – Short Answer Questions
1. What is a solution?
2. What is the difference between a solute and a solvent?
3. Why is salt water considered a uniform mixture?
4. What is meant by a saturated solution?
5. What is meant by solubility?
6. Why does oil float on water?
7. Why does ice float on water?
8. Why should we read the measuring cylinder at eye level?
Section E – Give Reasons
1. Sugar dissolves in water but does not dissolve easily in oil.
2. A bottle is often made tall and narrow for measuring liquids more easily.
3. An unpeeled orange can float while a peeled orange may sink.
4. Cold water can contain more dissolved oxygen than warm water.
Section F – Numerical Questions
Density = Mass ÷ Volume
1. A metal object has a mass of 180 g and a volume of 30 cm³. Find its density.
2. A wooden block has a mass of 240 g and a volume of 400 cm³. Find its density.
3. A stone has a mass of 360 g and a volume of 120 cm³. Calculate its density. Will it float or sink in water?
4. An object has a density of 5 g/cm³ and a volume of 20 cm³. Find its mass.
5. A liquid has a mass of 150 g and occupies 200 mL. Calculate its density.
6. A bottle can hold 3 litres of water. If 750 mL of water is already inside it, how much more water can it hold?
7. A solid is placed in a measuring cylinder. The water level rises from 45 mL to 68 mL. Find the volume of the solid.
8. A block has a mass of 790 g and a density of 7.9 g/cm³. Find its volume.
Section G – Application-Based Questions
1. A student adds sugar to a glass of water and stirs it. After adding several spoons, some sugar remains at the bottom. What does this tell you about the solution?
2. Two students prepare solutions. Student A dissolves 2 spoons of salt in 100 mL water. Student B dissolves 4 spoons of salt in 100 mL water. Which solution is more concentrated? Give a reason.
3. A cold drink contains dissolved carbon dioxide. What may happen to the gas if the drink becomes warm?
4. A student puts an egg into plain water and it sinks. She adds salt and stirs the water. After adding enough salt, the egg starts floating. Explain why.
5. A piece of clay is shaped into a ball and then flattened into a thin sheet. Has its density changed? Explain.
Section H – Think and Reason
1. A student says, “If I add more and more salt, all of it will always dissolve.” Do you agree? Explain.
2. Two objects have the same mass, but one occupies more space. Which object has lower density? Why?
3. Why can fish and other aquatic organisms be affected when water becomes too warm?
4. A stone and a wooden block have the same volume. The stone has greater mass. Which one has greater density? Explain.
Section I – Complete the Table
| Situation | What happens? | Reason |
|---|---|---|
| More salt is added to a saturated solution | ||
| Water is heated | ||
| Oil is poured into water | ||
| Ice is placed in water | ||
| A solid is placed in a measuring cylinder |
Section J – Match the Following
| Column A | Column B |
|---|---|
| 1. Solute | a. Mass ÷ Volume |
| 2. Solvent | b. Space occupied by an object |
| 3. Density | c. Substance that dissolves |
| 4. Volume | d. Substance in which solute dissolves |
| 5. Saturated solution | e. Cannot dissolve more solute at a given temperature |
Section K – Challenge Corner
1. Three liquids have densities of 0.8 g/cm³, 1 g/cm³ and 1.3 g/cm³. Which liquid will float on water and which will sink? Explain.
2. A student has 500 mL of water and wants to prepare a concentrated salt solution. What could the student do to make the solution more concentrated?
3. A solid has a mass of 250 g. When placed in a measuring cylinder, the water level rises from 60 mL to 110 mL. Find its density and predict whether it will float or sink in water.
4. Why does increasing pressure generally affect the density of gases more noticeably than the density of liquids or solids?
Section L – Activity-Based Questions
Activity 1: Salt and Water
Take equal amounts of water in three glasses. Add different amounts of salt to each glass and stir.
- Which glass has the most concentrated solution?
- Which glass becomes saturated first?
- What happens to extra salt after saturation?
Activity 2: Floating and Sinking
Observe an orange, a stone and a small piece of wood in water.
- Which objects float?
- Which objects sink?
- How is density related to your observations?
Activity 3: Measuring Volume
Use a measuring cylinder to find the volume of a small irregular stone by the displacement method.
- Record the initial water level.
- Place the stone carefully in the water.
- Record the final water level.
- Calculate the volume of the stone.
Quick Revision
| Concept | Remember |
|---|---|
| Solution | Uniform mixture of solute and solvent |
| Solute | Substance that dissolves |
| Solvent | Substance in which solute dissolves |
| Saturated solution | Cannot dissolve more solute at that temperature |
| Density | Mass ÷ Volume |
| Volume of irregular solid | Final water level − Initial water level |
| 1 mL | 1 cm³ |
| Floating | Object is generally less dense than the liquid |
| Ice | Floats because it is less dense than liquid water |
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