The Amazing World of Solutes, Solvents, and Solutions Class 8 Extra Questions and Answers Science Chapter 9

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Class 8 Science Chapter 9 The Amazing World of Solutes, Solvents, and Solutions Extra Questions

Class 8 Science Chapter 9 Extra Questions on The Amazing World of Solutes, Solvents, and Solutions

The Amazing World of Solutes, Solvents, and Solutions Class 8 Very Short Question Answer

Question 1.
What is a solute?
Answer:
A solute is the solid or smaller amount of a substance that dissolves in a solvent to form a solution.

Question 2.
Does oil float or sink in water?
Answer:
Oil floats in water.

Question 3.
What is a solution?
Answer:
A uniform mixture of two or more substances in which one acts as solute and the other acts as a solvent.

Question 4.
What tool is used to measure the volume of a liquid?
Answer:
Measuring cylinder.

Question 5.
What happens to the solubility of gases when pressure increases?
Answer:
Solubility increases.

Question 6.
What instrument is used to measure the mass of an object?
Answer:
A balance is used to measure mass of an object.

Question 7.
What is meant by the relative density of any substance with respect to water?
Answer:
It is the ratio of the density of a substance to the density of water.

Question 8.
What is the SI unit of density?
Answer:
The SI unit of density is kilogram per cubic metre $\left(\mathrm{kg} / \mathrm{m}^3\right)$.

Question 9.
Why does sugar dissolve faster in hot tea than in cold tea?
Answer:
This is because solubility of solids increases with temperature, so sugar dissolves faster in hot tea.

Question 10.
What is the curve surface of liquid in a measuring cylinder called?
Answer:
Meniscus.

The Amazing World of Solutes, Solvents, and Solutions Class 8 Short Question Answer

Question 1.
Why does Oral Rehydration Solution (ORS) taste the same in every sip?
Answer:
Every sip of ORS tastes the same because when sugar and salt are added to water, they form a uniform mixture in which the components are evenly distributed throughout.

Question 2.
What is the difference between uniform and non-uniform mixtures? Give examples.
Answer:
Uniform mixtures (solutions) have their components evenly distributed, such as salt dissolved in water. Non-uniform mixtures have components that are not evenly distributed and can be seen separately, such as chalk powder mixed with water.

Question 3.
Describe the traditional method of making salt in Ningel village.
Answer:
The salt solution is collected and boiled in large metal pans over firewood kilns. Once the water evaporates, salt crystals are formed, shaped into round salt cakes using banana leaves and handmade tools, and then wrapped in a traditional cloth called phanek.

Question 4.
How did Asima Chatterjee contribute to science?
Answer:
She worked on medicinal plants and developed anti-epileptic and anti-malarial drugs using solvents and solutions. She was awarded with the Padma Bhushan and Shanti Swarup Bhatnagar Award in the field of chemical science.

Question 5.
Why was bamboo commonly used to make rafts and small boats in ancient times?
Answer:
Bamboo was used for building boats and rafts because it is lightweight, hollow, and floats easily on water. People tied bamboo poles together to make rafts for fishing, transport, and trade. Even today, bamboo boats are used in some places for travel and tourism.

The Amazing World of Solutes, Solvents, and Solutions Class 8 Long Question Answer

Question 1.
How does temperature affect the solubility of solids and gases in liquids? Explain with examples.
Answer:
Temperature has opposite effects on the solubility of solids and gases in liquids.

• For solids, solubility generally increases with temperature. When water is heated, the increased movement of molecules allows more solute particles to dissolve.
• For gases, solubility decreases as the temperature increases. When water is heated, gas molecules gain energy and escape from the solution more easily.

Question 2.
Explain in detail why ice floats on water, and how the structure of water particles changes during freezing.
Answer:
Ice floats on water because its density is lower than that of liquid water. Water has a unique property-its density is highest at 4°C, meaning it is heaviest at that temperature. As water cools further and freezes at 0°C, its particles rearrange in a way that takes up more space.

This structural change is called expansion. Since the same amount of water now occupies a larger volume, its density decreases. This lower density causes ice to float on the surface of water. This floating ice forms an insulating layer, helping to keep the water beneath it warm enough for fish and other aquatic animals to survive in very cold weather.

Question 3.
Define the term ‘density’. How does pressure affect the density in different states of matter?
Answer:
Density is defined as the mass present in a unit volume of a substance.
Mathematically, Density \(=\frac{\text { Mass }}{\text { Volume }}\)
Effect of pressure on density: Pressure affects density differently depending on the state of matter.

• For gases, density increases with an increase in pressure.
• For liquids, pressure has a small effect because they are nearly incompressible.
• For-solids, pressure has very little effect than liquids because the particles in solids are very close to each other.

The Amazing World of Solutes, Solvents, and Solutions Class 8 Skill-Based Questions

Question 1.
Observe the given images and answer the following questions.
(i) If the volume of both oil and water is 100 mL , which liquid is denser?
(ii) Will the density change if the size of the bottle changes?
(iii) Find the density of oil in g/mL
Answer:
(i) Water is denser than oil.

(ii) No, the density does not change if the size of the bottle changes.
(iii)
Density = \(\frac{\text { Mass }}{\text { Volume }}\) = 90 g / 100 mL
= 0.9 g/ mL
The density of oil is 0.9g/mL

Question 2.
Observe the given image and answer the following questions.
(i) What do you see in the image?
(ii) Why does the egg sink to the bottom?
(iii) What can be done to make it float?
Answer:
(i) An egg sinking in a glass of water.

(ii) Because the density of the egg is greater than that of water.
(iii) To make the egg float, salt can be added to the water, As salt increases the density of water. When the water becomes denser than the egg, the egg starts to float.

The Amazing World of Solutes, Solvents, and Solutions Class 8 Quiz Questions

Question 1.
Name a gas that dissolves in water.
Answer:
Oxygen

Question 2.
What happens when a solute dissolves in a solvent?
Answer:
It forms a solution

Question 3.
In which unit the weight is measured?
Answer:
newton (N)

Question 4.
What is the most commonly used solvent in traditional Indian medicine?
Answer:
Water

Question 5.
Who was the first Indian woman to receive the Shanti Swarup Bhatnagar Award in the field of chemical science?
Answer:
Asima Chatterjee

Question 6.
What type of mixture is formed when chalk powder is mixed with water?
Answer:
Non-uniform mixture

Question 7.
What traditional materials were used in ancient times to make boats?
Answer:
Bamboo and wood

Question 8.
What term describes a solution in which more solute can still be dissolved?
Answer:
Unsaturated solution

Question 9.
Which apparatus is commonly used to measure the volume of a liquid?
Answer:
Measuring cylinder

Question 10.
What is the formula for calculating the volume of a cuboid?
Answer:
Volume = length (l) × width (w) × height (h)

The Amazing World of Solutes, Solvents, and Solutions Class 8 Case Based Questions

Question 1.
Riya had an upset stomach, so her mother gave her an Oral Rehydration Solution (ORS) made at home by mixing salt, sugar, and water. She noticed that every sip tasted the same and asked why. Her mother explained that all the ingredients were completely dissolved, forming a uniform solution.
I. What type of mixture is ORS?
II. What are the solute and solvent in ORS?
III. Why does every sip of ORS taste the same?
OR
Why is ORS given to someone with an upset stomach?
Answer:
I. It is a uniform mixture or solution.
II. Salt and sugar are the solutes, and water is the solvent in ORS.
III. This is because the solutes are evenly distributed throughout the solvent, forming a uniform solution.
OR
ORS helps restore lost fluids and minerals, preventing dehydration.

Question 2.
During a science activity, Aditya kept adding salt to a glass of water while stirring. Initially, the salt dissolved. After a few spoons, some salt settled at the bottom. He then heated the solution, and the undissolved salt dissolved again.
I. What is the term for the solution when salt no longer dissolves in water?
II. What happened when the solution was heated?
III. What does this experiment show about the effect of temperature on solubility?
OR
What role did stirring play in this experiment?
Answer:
I. Saturated solution.
II. More salt dissolved in water.
III. Solubility of most solutes increases with increase in temperature.
OR
Stirring helped the salt dissolve faster in the water.

The Amazing World of Solutes, Solvents, and Solutions Extra Questions for Practice

Multiple Choice Questions

Question 1.
What is the formula for density?
(a) Density = Volume × Mass
(b) Density = Mass ÷ Volume
(c) Density = Mass + Volume
(d) Density = Weight ÷ Volume

Question 2.
Which of the following mixtures is uniform in nature?
(a) Sand and water
(b) Oil and water
(c) Salt and water
(d) Chalk powder and water

Question 3.
When oil is added to water, it floats. Why?
(a) Oil has more mass
(b) Oil is lighter and less dense than water
(c) Oil dissolves in water
(d) Water is less dense than oil

Question 4.
Read the given statements and select the correct option.
Assertion (A): Gases are highly compressible.
Reason (R): Gases have large interparticle spaces between their particles.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false.
(d) A is false but R is true.

Question 5.
Match the terms in Column A with their correct descriptions in Column B:
Column A — Column B
(i) Millilitre — (p) Unitless
(ii) Weight — (q) No more solute dissolves
(iii) Relative density — (r) Equivalent to 1 centimetre cube
(iv) Concentrated solution — (s) Measured in newtons
(a) (i)-(s), (ii)-(r), (iii)-(q), (iv)-(p)
(b) (i)-(s), (ii)-(p), (iii)-(q), (iv)-(r)
(c) (i)-(r), (ii)-(s), (iii)-(p), (iv)-(q)
(d) (i)-(q), (ii)-(r), (iii)-(s), (iv)-(p)

Very Short Answer Type Questions

Question 1.
Define solubility.

Question 2.
What type of solution contains the maximum amount of solute at a given temperature?

Question 3.
Are mass and weight the same terms in the context of science?

Question 4.
Name two traditional Indian systems of medicine that use water as a solvent.

Question 5.
If a stone causes the water level in a measuring cylinder to rise from 40 mL to 45 mL , what is the volume of the stone?

Short Answer Type-I Questions

Question 1.
What is the difference between dilute and concentrated solutions?

Question 2.
An aluminium block has a mass of 27 g and a volume of 10cm³. What is its density?

Question 3.
Define the following terms:
(a) Saturated solution
(b) Unsaturated solution

Question 4.
Why does sand sink while sawdust floats when mixed with water?

Question 5.
Name the solute and solvent present in the chashni (sugar syrup) used in a traditional Indian sweet Gulab jamun.

Short Answer Type-II Questions

Question 1.
Suppose you keep adding sugar to tea, and after a point, it stops dissolving. What kind of solution is it now, and what does this tell you about solubility?

Question 2.
Write true (T) or false (F) against the following statements.
(i) Traditional wooden logs were used to make rafts in ancient times. (  )
(ii) Ice is denser than liquid water, so it sinks. (  )
(iii) Gases like oxygen dissolve better in cold water. (  )

Question 3.
How is the volume of an irregular-shaped object (like a stone) measured?

Question 4.
What are solute, solvent, and solution? Explain with diagram.

Question 5.
You have two solutions: one with 2 spoons of salt in 100 mL of water and another with 4 spoons of salt in 50 mL of water. Which solution is more concentrated? Explain.

Long Answer Type Questions

Question 1.
Describe the effect of temperature on the density of a substance.

Question 2.
Object A has a mass of 400 g and a volume of 60cm³. Object B has a mass of 600 g and a volume of 80cm³. Which object is denser?

Question 3.
Draw a diagram representing the different layers of Earth. Explain the density of different layers on moving towards the centre of the Earth.

Suggested Projects And Activities

Question 1.
Research about Indian saltwater lakes such as Sambhar and Lonar Lake and compare their salt concentration in the water and investigate why aquatic life is limited in these water bodies. Prepare a project report with your findings.

Question 2.
Conduct a classroom debate on the topic “Can we live without salt?”
Explore the importance of salt in our diet, health, and everyday life. Form two teams to present arguments for and against the idea. Conclude with a class discussion.