Solution chapter 9 class 8 science

📘 Chapter 9 – The Amazing World of Solutes, Solvents, and Solutions

Complete Solutions with Explanation

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🔹 Q1. True or False (Correct the false statements)

1. Oxygen gas is more soluble in hot water than in cold water.
2. A mixture of sand and water is a solution.
3. The amount of space occupied by an object is called its mass.
4. An unsaturated solution has more solute dissolved than a saturated solution.
5. The mixture of gases in the atmosphere is a solution.

1. False – Oxygen is more soluble in cold water.
2. False – Sand and water form a non-uniform mixture.
3. False – Space occupied is called volume.
4. False – Saturated solution has more solute.
5. True – Air is a uniform mixture of gases.

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🔹 Q2. Fill in the blanks

1. The solid is _________ in water and the ________ in water level is measured.
2. The maximum amount of _________ dissolved in _________ is solubility.
3. Density __________ with increase in temperature.
4. The solution is called a __________ solution.

1. immersed, rise
2. solute, solvent
3. decreases
4. saturated

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🔹 Q3. Oil floats on water. What does this tell you?

Correct option: Water is denser than oil.
Explanation: Oil floats because it has lower density than water.

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🔹 Q4. Density of stone sculpture

Mass = 225 g, Volume = 90 cm³

Density = Mass ÷ Volume
= 225 ÷ 90 = 2.5 g/cm³
The stone will sink in water because its density is greater than water.

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🔹 Q5. Most appropriate statement

Correct: No more solute can be dissolved in a saturated solution at that temperature.
Other options are incorrect because they describe unsaturated solutions or wrong conditions.

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🔹 Q6. Bottle capacity

Total capacity = 2000 mL
Water added = 500 mL
Remaining = 1500 mL

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🔹 Q7. Density of an object

Density = 400 ÷ 40 = 10 g/cm³

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🔹 Q8. Orange experiment

Unpeeled orange floats due to air trapped in peel.
Peeled orange sinks because density increases.

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🔹 Q9. Which object is denser?

Object A density = 5 g/cm³
Object B density = 4 g/cm³
Object A is denser.

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🔹 Q10. Density of modelling clay

Density remains the same because mass and volume do not change.

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🔹 Q11. Volume of iron block

Volume = 600 ÷ 7.9 ≈ 75.9 cm³

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🔹 Q12. Effect of heating on density

Density decreases on heating because volume increases.

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🧠 MCQ Quiz – Solutes, Solvents & Density

Class: 8 | Chapter: Solutions

1. A uniform mixture is called:

Suspension
Solution
Colloid

2. Which is the solute in salt water?

Salt
Water
Air

3. A solution that cannot dissolve more solute is:

Unsaturated
Saturated
Dilute

4. Solubility of solids generally _____ with temperature.

Increases
Decreases
Remains same

5. Which gas dissolves more in cold water?

Oxygen
Nitrogen
Hydrogen

6. Density is equal to:

Volume ÷ Mass
Mass ÷ Volume
Mass × Volume

7. Which object will float on water?

Oil
Iron nail
Stone

8. Ice floats on water because:

Ice is less dense than water
Ice is heavier
Ice dissolves in water

9. The curved surface of liquid in a cylinder is called:

Meniscus
Curve
Arc

10. Which mixture is a solution?

Sugar + water
Sand + water
Chalk + water