---
title: "NCERT Solutions Class 8 Science The Amazing World of Solutes, Solvents, and Solutions"
url: https://www.swavid.com/science/class/8/chapter/the-amazing-world-of-solutes-solvents-and-solutions/ncert-solutions
dateModified: 2026-10-07T16:15:53+00:00
---

# NCERT Solutions Class 8 Science The Amazing World of Solutes, Solvents, and Solutions

This chapter's questions cover concepts related to solutes, solvents, solutions, concentration, solubility, and density. They test students' understanding through true/false statements, fill-in-the-blanks, numerical calculations, and conceptual reasoning exercises.

Free PDF (8 pages): https://www.swavid.com/api/seo/pdf/ncert/science/class-8/swavid-ncert-solutions-class-8-science-chapter-9-the-amazing-world-of-solutes-solvents-and-solutions-1c96eca055.pdf

## Probe and ponder

### Question 1

*2 marks · Very short answer*

What do you think is happening in the picture above?

**Solution**

1. The picture depicts the Dandi March or people gathering salt from sea water along the coast.
2. It shows individuals collecting salt crystals that remain after sea water evaporates.

**Answer:** People are gathering salt from sea water along the coast.

> Common mistake: Confusing the salt-making process with general fishing or washing activities.

### Question 2

*3 marks · Short answer*

What happens when you add too much sugar to your tea and it stops dissolving? How can you solve this problem?

**Solution**

1. When too much sugar is added and it stops dissolving, the tea has become a saturated solution at that temperature.
2. The undissolved sugar settles at the bottom because the liquid has reached its limit of dissolving solute.
3. This problem can be solved by heating the tea, as the solubility of most substances increases with an increase in temperature.

**Answer:** The tea forms a saturated solution. It can be solved by heating the tea to increase the solubility of sugar.

> Common mistake: Stating that adding more water is the only way, without mentioning temperature change.

### Question 3

*3 marks · Short answer*

Why do sugar and salt dissolve in water but not in oil? Why is water considered a good solvent?

**Solution**

1. Sugar and salt dissolve in water because water is a polar solvent that can interact with and separate their particles.
2. They do not dissolve in oil because oil is a non-polar solvent with different chemical properties.
3. Water is considered a good solvent because it can dissolve a wide variety of solutes, including solids, liquids, and gases.

**Answer:** Sugar and salt dissolve in water due to its ability to interact with solute particles, while oil has different properties. Water dissolves many substances.

> Common mistake: Assuming all liquids dissolve all types of solutes equally.

### Question 4

*3 marks · Short answer*

Why are water bottles usually tall and cylindrical in shape instead of spherical?

**Solution**

1. Water bottles are made tall and cylindrical so that they occupy less base area, making them easier to hold and grip with one hand.
2. A cylindrical shape distributes pressure evenly and provides better structural strength compared to a sphere.
3. Spherical bottles would roll easily, take up more storage space, and be difficult to stack or carry.

**Answer:** Cylindrical bottles are easier to grip, occupy less base space, and are more stable than spherical ones.

> Common mistake: Giving reasons related only to manufacturing without considering handling and storage.

## Keep the curiosity alive

### Question 1

*1 mark · True or false*

State whether the statements given below are True [T] or False [F]. Correct the false statement(s).
(i) Oxygen gas is more soluble in hot water rather than in cold water.
(ii) A mixture of sand and water is a solution.
(iii) The amount of space occupied by any object is called its mass.
(iv) An unsaturated solution has more solute dissolved than a saturated solution.
(v) The presence of different gases in the atmosphere is also a uniform mixture.

**Part (i)**

1. Oxygen gas is less soluble in hot water rather than in cold water.

Answer (i): False

**Part (ii)**

1. A mixture of sand and water is a non-uniform mixture.

Answer (ii): False

**Part (iii)**

1. The amount of space occupied by any object is called its volume.

Answer (iii): False

**Part (iv)**

1. A saturated solution has more solute dissolved than an unsaturated solution.

Answer (iv): False

**Part (v)**

1. The presence of different gases in the atmosphere is a uniform mixture.

Answer (v): True

**Answer:** (i) False, (ii) False, (iii) False, (iv) False, (v) True

> Common mistake: Confusing solubility of gases with solids, where gas solubility decreases with temperature.

### Question 2

*1 mark · Fill in the blank*

Fill in the blanks.
(i) The volume of a solid can be measured by the method of displacement, where the solid is __________ in water and the ____________ in water level is measured.
(ii) The maximum amount of _______________ dissolved in _______________ at a particular temperature is called solubility at that temperature.
(iii) Generally, the density ____________ with increase in temperature.
(iv) The solution in which glucose has completely dissolved in water, and no more glucose can dissolve at a given temperature, is called a __________ solution of glucose.

**Part (i)**

1. The volume of a solid is measured by submerging it in water and noting the change in water level.

Answer (i): submerged, change

**Part (ii)**

1. Solubility is defined as the maximum amount of solute dissolved in a fixed quantity of solvent at a particular temperature.

Answer (ii): solute, solvent

**Part (iii)**

1. Generally, the density of a substance decreases with an increase in temperature due to an increase in volume.

Answer (iii): decreases

**Part (iv)**

1. A solution in which no more solute can dissolve at a given temperature is called a saturated solution.

Answer (iv): saturated

**Answer:** (i) submerged, change (ii) solute, solvent (iii) decreases (iv) saturated

> Common mistake: Writing unsaturated instead of saturated.

### Question 3

*1 mark · MCQ*

You pour oil into a glass containing some water. The oil floats on top. What does this tell you?

- Oil is denser than water
- Water is denser than oil
- Oil and water have the same density
- Oil dissolves in water

**Solution**

1. Oil floats on water because it is lighter than water, meaning its density is less than that of water.
2. Therefore, water is denser than oil.

**Answer:** (ii) Water is denser than oil

> Common mistake: Assuming floating objects are always denser.

### Question 4

*3 marks · Numerical*

A stone sculpture weighs $225\text{ g}$ and has a volume of $90\text{ cm}^3$. Calculate its density and predict whether it will float or sink in water.

**Solution**

1. Given: Mass of stone sculpture = $225\text{ g}$, Volume = $90\text{ cm}^3$
2. Formula: $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$
3. Substitution: $\text{Density} = \frac{225\text{ g}}{90\text{ cm}^3}$
4. Result: $2.5\text{ g/cm}^3$
5. Prediction: Since the density of the stone ($2.5\text{ g/cm}^3$) is greater than the density of water ($1\text{ g/cm}^3$), it will sink in water.

**Answer:** Density = $2.5\text{ g/cm}^3$; it will sink in water.

> Common mistake: Forgetting to compare with the density of water to predict sinking or floating.

### Question 5

*3 marks · Short answer*

Which one of the following is the most appropriate statement, and why are the other statements not appropriate?
(i) A saturated solution can still dissolve more solute at a given temperature.
(ii) An unsaturated solution has dissolved the maximum amount of solute possible at a given temperature.
(iii) No more solute can be dissolved into the saturated solution at that temperature.
(iv) A saturated solution forms only at high temperatures.

**Solution**

1. Statement (iii) is the most appropriate because a saturated solution has reached its maximum limit of dissolution at a given temperature.
2. Statement (i) is incorrect because a saturated solution cannot dissolve more solute at that temperature.
3. Statements (ii) and (iv) are incorrect because an unsaturated solution can still dissolve more solute, and saturated solutions can form at any temperature.

**Answer:** Statement (iii) is most appropriate as it correctly defines the condition of a saturated solution.

> Common mistake: Confusing saturated and unsaturated solution properties.

### Question 6

*3 marks · Numerical*

You have a bottle with a volume of $2\text{ litres}$. You pour $500\text{ mL}$ of water into it. How much more water can the bottle hold?

**Solution**

1. Given: Total volume of the bottle = $2\text{ litres} = 2000\text{ mL}$, Volume of water poured = $500\text{ mL}$
2. Formula: $\text{Remaining capacity} = \text{Total volume} - \text{Volume poured}$
3. Substitution: $\text{Remaining capacity} = 2000\text{ mL} - 500\text{ mL}$
4. Result: $1500\text{ mL}$ or $1.5\text{ litres}$

**Answer:** $1500\text{ mL}$ (or $1.5\text{ litres}$)

> Common mistake: Not converting litres to millilitres before subtracting, or subtracting incorrectly.

### Question 7

*3 marks · Numerical*

An object has a mass of $400\text{ g}$ and a volume of $40\text{ cm}^3$. What is its density?

**Solution**

1. Given: $\text{Mass} = 400\text{ g}$, $\text{Volume} = 40\text{ cm}^3$
2. Formula: $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$
3. Substitution: $\text{Density} = \frac{400\text{ g}}{40\text{ cm}^3}$
4. Result: $10\text{ g/cm}^3$

**Answer:** $10\text{ g/cm}^3$

> Common mistake: Dividing volume by mass instead of mass by volume.

### Question 8

*3 marks · Short answer*

Analyse Fig. 9.25a and 9.25b. Why does the unpeeled orange float, while the peeled one sinks? Explain.

**Solution**

1. The unpeeled orange floats because the peel contains tiny trapped air pockets, making its overall density less than that of water.
2. When the orange is peeled, these air pockets are removed, and the compact fruit has a higher density than water.
3. As a result, the peeled orange sinks to the bottom while the unpeeled orange floats.

**Answer:** The unpeeled orange floats due to trapped air making it less dense, whereas the peeled orange is denser than water and sinks.

> Common mistake: Stating that weight changes instead of density due to air trapped in the peel.

### Question 9

*3 marks · Numerical*

Object A has a mass of $200\text{ g}$ and a volume of $40\text{ cm}^3$. Object B has a mass of $240\text{ g}$ and a volume of $60\text{ cm}^3$. Which object is denser?

**Solution**

1. Given Object A: $\text{Mass} = 200\text{ g}$, $\text{Volume} = 40\text{ cm}^3$
2. Given Object B: $\text{Mass} = 240\text{ g}$, $\text{Volume} = 60\text{ cm}^3$
3. Density of Object A: $\frac{200\text{ g}}{40\text{ cm}^3} = 5\text{ g/cm}^3$
4. Density of Object B: $\frac{240\text{ g}}{60\text{ cm}^3} = 4\text{ g/cm}^3$
5. Result: Object A is denser.

**Answer:** Object A is denser ($5\text{ g/cm}^3$ versus $4\text{ g/cm}^3$).

> Common mistake: Comparing mass or volume directly without calculating density.

### Question 10

*3 marks · Short answer*

Reema has a piece of modeling clay that weighs $120\text{ g}$. She first moulds it into a compact cube that has a volume of $60\text{ cm}^3$. Later, she flattens it into a thin sheet. Predict what will happen to its density.

**Solution**

1. The density of an object is independent of its shape or size.
2. When the modeling clay is flattened into a thin sheet, its mass and volume remain unchanged.
3. Therefore, its density will remain the same ($2\text{ g/cm}^3$).

**Answer:** The density of the modeling clay will remain the same.

> Common mistake: Thinking that changing the shape of an object changes its density.

### Question 11

*3 marks · Numerical*

A block of iron has a mass of $600\text{ g}$ and a density of $7.9\text{ g/cm}^3$. What is its volume?

**Solution**

1. Given: Mass of the iron block = $600\text{ g}$, Density of iron = $7.9\text{ g/cm}^3$
2. Formula: $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$, which means $\text{Volume} = \frac{\text{Mass}}{\text{Density}}$
3. Substitution: $\text{Volume} = \frac{600}{7.9}\text{ cm}^3$
4. Result: $75.95\text{ cm}^3$

**Answer:** $75.95\text{ cm}^3$

> Common mistake: Dividing density by mass instead of mass by density.

### Question 12

*3 marks · Short answer*

You are provided with an experimental setup as shown in Fig. 9.26a and 9.26b. On keeping the test tube (Fig 9.26b) in a beaker containing hot water ($\sim 70\text{ }^\circ\text{C}$), the water level in the glass tube rises. How does it affect the density?

**Solution**

1. When the test tube is placed in hot water, the water inside the test tube gets heated and expands in volume.
2. As temperature increases, the volume of the water increases while its mass remains the same.
3. Since $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$, an increase in volume causes the density of the water inside the test tube to decrease.

**Answer:** The density of the water inside the test tube decreases as its volume increases upon heating.

> Common mistake: Stating that density increases when temperature increases.

## Frequently asked questions

### How many questions are there in the Class 8 Science Chapter 9 NCERT solutions on this page?

This chapter contains a total of 16 questions divided across two sections called Probe and ponder and Keep the curiosity alive. You can find step-by-step answers for all of them in SwaVid's free PDF available on this page.

### Which topics are covered in the Class 8 Science Chapter 9 exercise questions?

The questions cover important concepts like the Dandi March and salt collection, saturated solutions, the effect of temperature on solubility, shape and volume advantages, and solvents. Other questions focus heavily on density, mass, volume, and the floating of objects.

### What are the different question types included in these NCERT solutions?

The solutions include very short answer, short answer, fill in the blanks, multiple choice questions, true or false, and numerical problems. SwaVid provides detailed explanations for each type to help students understand the concepts clearly.

### Which question type is considered difficult in this chapter and how should I approach it?

Numerical questions involving density, mass, and volume are often found challenging by students. To solve them correctly, you should first write down the given values, apply the correct formula, and check your units step by step.

### Are the SwaVid free PDF and answers for this chapter available here?

Yes, SwaVid's free PDF and complete step-by-step solutions for this chapter are available on this page only. Writing answers according to these structured points will help you score full marks in your Class 8 examinations.

## Related pages

- [Class 8 Science chapters](https://www.swavid.com/science/class/8)

Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student