✅ True or False (10 Questions)

(CBSE Class 8 Standard | Good Quality)

1. A mixture is formed when two or more substances are mixed and each retains its own properties.
   True hecu108

2. The components of a mixture react chemically with each other.
   False
   (Components do not react chemically in a mixture.) hecu108

3. Sprout salad is an example of a non-uniform mixture.
   True hecu108

4. Sugar dissolved in water forms a uniform mixture.
   True hecu108

5. Air is a uniform mixture of gases like nitrogen, oxygen, and carbon dioxide.
   True hecu108

6. A pure substance can be separated into simpler substances by physical methods.
   False
   (Pure substances cannot be separated by physical processes.) hecu108

7. Elements are substances that cannot be broken down into simpler substances.
   True hecu108

8. Water is an element because it is made up of hydrogen and oxygen.
   False
   (Water is a compound, not an element.) hecu108

9. Compounds are formed when elements combine in a fixed ratio and have new properties.
   True hecu108

10. When iron filings and sulfur are heated, a compound called iron sulfide is formed.
    True

✅ Fill in the Blanks (10 Questions)

(CBSE Class 8 Standard | Good Quality)

1. A mixture is formed when two or more substances are mixed without __________ change.
   Answer: chemical hecu108

2. A mixture in which components are evenly distributed is called a __________ mixture.
   Answer: uniform hecu108

3. Sprout salad and poha are examples of __________ mixtures.
   Answer: non-uniform hecu108

4. Air is a mixture of gases like nitrogen, oxygen, carbon dioxide, and __________ vapour.
   Answer: water hecu108

5. A substance that contains only one kind of particles is called a __________ substance.
   Answer: pure hecu108

6. An element is made up of only one type of __________.
   Answer: atom hecu108

7. When two or more elements combine chemically in a fixed ratio, they form a __________.
   Answer: compound hecu108

8. Water is a compound made of hydrogen and __________.
   Answer: oxygen hecu108

9. The components of a mixture can be separated by __________ methods.
   Answer: physical hecu108

10. Heating iron filings with sulfur forms a new compound called iron __________.
    Answer: sulfide

✅ Multiple Choice Questions (15 MCQs)

(CBSE Class 8 Standard | Good Quality)

1. A mixture is formed when substances are combined:

A. Chemically
B. Without chemical reaction
C. Only by heating
D. In a fixed ratio
✅ Answer: B hecu108

2. Which of the following is a non-uniform mixture?

A. Salt solution
B. Air
C. Sprout salad
D. Sugar solution
✅ Answer: C hecu108

3. Air is an example of:

A. Element
B. Compound
C. Uniform mixture
D. Non-uniform mixture
✅ Answer: C hecu108

4. A pure substance contains:

A. Many different particles
B. Only one kind of particles
C. Only gases
D. Only solids
✅ Answer: B hecu108

5. Elements are substances that:

A. Can be broken down easily
B. Cannot be broken down into simpler substances
C. Are always mixtures
D. Contain two atoms
✅ Answer: B hecu108

6. Water is a:

A. Mixture
B. Element
C. Compound
D. Alloy
✅ Answer: C hecu108

7. A compound is formed when elements combine:

A. In any proportion
B. Without chemical change
C. Chemically in a fixed ratio
D. Only physically
✅ Answer: C hecu108

8. Which of the following is an element?

A. Oxygen
B. Water
C. Salt
D. Sugar
✅ Answer: A hecu108

9. The components of a mixture can be separated by:

A. Chemical methods only
B. Physical methods
C. Nuclear reactions
D. Fixed ratio
✅ Answer: B hecu108

10. When iron filings and sulfur are heated, the product formed is:

A. Mixture
B. Iron oxide
C. Iron sulfide
D. Sulfur dioxide
✅ Answer: C hecu108

11. Which of the following is a compound?

A. Nitrogen
B. Copper
C. Carbon dioxide
D. Air
✅ Answer: C hecu108

12. In a mixture, components:

A. Lose their properties
B. Retain their properties
C. Form new substances
D. Combine in fixed ratio
✅ Answer: B hecu108

13. Brass is an example of:

A. Element
B. Compound
C. Alloy
D. Solution
✅ Answer: C hecu108

14. Stainless steel is made by mixing iron with:

A. Water
B. Sulfur
C. Carbon and chromium
D. Oxygen
✅ Answer: C hecu108

15. Which of these is NOT a mixture?

A. Air
B. ORS
C. Water
D. Sprout salad
✅ Answer: C

✅ Assertion–Reason Questions (10)

(CBSE Class 8 Standard | Good Quality)

Directions: Choose the correct option:

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

1.

Assertion (A): A mixture is formed without chemical change.
Reason (R): The components of a mixture retain their own properties.
✅ Answer: A hecu108

2.

Assertion (A): Air is a uniform mixture of gases.
Reason (R): Different gases are evenly distributed in air.
✅ Answer: A hecu108

3.

Assertion (A): Sprout salad is a uniform mixture.
Reason (R): Its components can be seen separately.
✅ Answer: D hecu108

4.

Assertion (A): Elements cannot be broken down into simpler substances.
Reason (R): Elements are made of only one type of atom.
✅ Answer: A hecu108

5.

Assertion (A): Water is an element.
Reason (R): Water is made up of hydrogen and oxygen.
✅ Answer: D hecu108

6.

Assertion (A): Compounds are formed by chemical combination of elements.
Reason (R): Elements combine in a fixed ratio to form compounds.
✅ Answer: A hecu108

7.

Assertion (A): Mixtures can be separated by physical methods.
Reason (R): No new substance is formed in a mixture.
✅ Answer: A hecu108

8.

Assertion (A): Iron and sulfur mixture can be separated using a magnet.
Reason (R): Iron retains its magnetic property in the mixture.
✅ Answer: A hecu108

9.

Assertion (A): Iron sulfide is a mixture.
Reason (R): Iron and sulfur combine chemically on heating.
✅ Answer: D hecu108

10.

Assertion (A): Alloys are mixtures of metals.
Reason (R): Alloys have improved properties compared to pure metals.
✅ Answer: B

✅ Very Short Answer Questions (10 Questions)

(2 Marks Each | CBSE Class 8 Standard | Good Quality)

1. What is a mixture?

Answer:
A mixture is a combination of two or more substances in which each substance retains its own properties and no chemical change occurs. hecu108

2. What is a uniform mixture?

Answer:
A uniform mixture is one in which the components are evenly distributed throughout and cannot be seen separately, such as salt solution. hecu108

3. Give one example of a non-uniform mixture.

Answer:
Sprout salad or poha is an example of a non-uniform mixture. hecu108

4. What is a pure substance?

Answer:
A pure substance is made up of only one kind of particles and has fixed composition and properties. hecu108

5. Define an element.

Answer:
An element is a pure substance made of only one type of atom and cannot be broken down into simpler substances. hecu108

6. Define a compound.

Answer:
A compound is a pure substance formed when two or more elements combine chemically in a fixed ratio. hecu108

7. Why is water called a compound?

Answer:
Water is called a compound because it is formed by chemical combination of hydrogen and oxygen in a fixed ratio. hecu108

8. How can mixtures be separated?

Answer:
Mixtures can be separated into their components by physical methods like filtration, evaporation, or using a magnet. hecu108

9. What is an alloy?

Answer:
An alloy is a mixture of two or more metals (or a metal and a non-metal) made to improve properties, such as brass or stainless steel. hecu108

10. What compound is formed when iron filings and sulfur are heated?

Answer:
When iron filings and sulfur are heated, a compound called iron sulfide is formed

✅ Short Answer Questions (10 Questions)

(3 Marks Each | CBSE Class 8 Standard | Good Quality)

1. Differentiate between uniform and non-uniform mixtures with examples.

Answer:
A uniform mixture has the same composition throughout and components are not visible separately, like salt solution or air. A non-uniform mixture has uneven distribution and components can be seen separately, like sprout salad or poha. hecu108

2. Explain the difference between an element and a compound.

Answer:
An element is a pure substance made of only one type of atom and cannot be broken down. A compound is formed when two or more elements combine chemically in a fixed ratio and has properties different from its elements. hecu108

3. Why can mixtures be separated by physical methods?

Answer:
Mixtures can be separated by physical methods because their components do not combine chemically. Each component retains its own properties, so methods like filtration, evaporation, or magnet separation can be used. hecu108

4. Describe the experiment of iron filings and sulfur mixture.

Answer:
When iron filings and sulfur are mixed, they form a mixture and iron can be separated using a magnet. On heating, they combine chemically to form iron sulfide, a compound with new properties, and magnet cannot separate iron anymore. hecu108

5. What are alloys? Give two examples.

Answer:
Alloys are mixtures of metals (or metal with non-metal) made to improve strength and resistance. Examples: Brass (copper + zinc) and stainless steel (iron + carbon + chromium). hecu108

6. Why does a compound have different properties from its elements?

Answer:
In a compound, elements combine chemically in a fixed ratio, forming a new substance. The new compound has properties different from the elements that formed it, like water being different from hydrogen and oxygen. hecu108

7. Explain why air is considered a mixture.

Answer:
Air is a mixture because it contains gases like nitrogen, oxygen, carbon dioxide, and water vapour. These gases are not chemically combined and can be separated. Each retains its own properties. hecu108

8. Give three differences between mixtures and compounds.

Answer:
Mixtures have variable composition, components retain properties, and can be separated physically. Compounds have fixed composition, new properties, and can only be separated chemically. hecu108

9. What is meant by physical change and chemical change in context of mixtures?

Answer:
In mixtures, substances combine without chemical change, so only physical change occurs. In compounds, elements combine chemically, resulting in chemical change and formation of a new substance. hecu108

10. How are minerals useful to us?

Answer:
Minerals are natural substances found in Earth’s crust. They are used to extract metals and make useful products like jewellery, tools, and construction materials.

✅ Case-Based Questions (4 Cases)

(4 Marks Each | Sub-questions: 1 + 1 + 2 Marks)
CBSE Competency-Based Standard

Case 1: Sprout Salad as a Mixture

Sprout salad is made by mixing sprouts, onion, tomato, cucumber, and spices. All the ingredients can be seen separately and can be picked out easily.

Questions:

Q1. (1 Mark) What type of mixture is sprout salad?
Answer: Non-uniform mixture hecu108

Q2. (1 Mark) Can the components of sprout salad be separated easily?
Answer: Yes hecu108

Q3. (2 Marks) Why is sprout salad called a mixture?
Answer:
Because its components are mixed physically, retain their properties, and can be separated without any chemical change. hecu108

Case 2: Air as a Mixture

Air contains nitrogen, oxygen, carbon dioxide, water vapour, and other gases. These gases are mixed uniformly and support life on Earth.

Questions:

Q1. (1 Mark) Name one gas present in air.
Answer: Oxygen / Nitrogen hecu108

Q2. (1 Mark) Is air a uniform mixture or non-uniform mixture?
Answer: Uniform mixture hecu108

Q3. (2 Marks) Why is air considered a mixture and not a compound?
Answer:
Because gases in air are not chemically combined, are present in variable proportions, and retain their own properties. hecu108

Case 3: Iron and Sulfur Experiment

Iron filings and sulfur powder form a mixture when mixed. Iron can be separated using a magnet. But when the mixture is heated, a new compound called iron sulfide is formed.

Questions:

Q1. (1 Mark) How can iron be separated from the mixture?
Answer: Using a magnet hecu108

Q2. (1 Mark) What compound is formed after heating iron and sulfur?
Answer: Iron sulfide hecu108

Q3. (2 Marks) Why is iron sulfide different from the mixture of iron and sulfur?
Answer:
Iron sulfide is a compound formed by chemical reaction with new properties, and its components cannot be separated by physical methods. hecu108

Case 4: Alloys in Daily Life

Stainless steel is made by mixing iron with carbon and chromium. Brass is made from copper and zinc. These mixtures are called alloys and are stronger than pure metals.

Questions:

Q1. (1 Mark) What are alloys?
Answer: Mixtures of metals (or metal with non-metal). hecu108

Q2. (1 Mark) Give one example of an alloy.
Answer: Brass / Stainless steel hecu108

Q3. (2 Marks) Why are alloys preferred over pure metals?
Answer:
Alloys have improved properties like greater strength, hardness, and resistance to rust and corrosion compared to pure metals.

✅ Long Answer Questions (5 Questions)

(5 Marks Each | CBSE Class 8 Standard | High Quality Answers)

1. Explain mixtures and their types with suitable examples.

Answer:
A mixture is formed when two or more substances are mixed together without any chemical reaction. Each substance retains its own properties.

Types of Mixtures:

1. Uniform Mixture (Homogeneous):
   Components are evenly distributed and cannot be seen separately.
   Examples: Salt solution, air.
2. Non-uniform Mixture (Heterogeneous):
   Components are not evenly distributed and can be seen separately.
   Examples: Sprout salad, poha.

Thus, mixtures are common in daily life and can be separated by physical methods. hecu108

2. Differentiate between elements, compounds, and mixtures.

Answer:

Feature	Element	Compound	Mixture
Composition	One type of atom	Two or more elements chemically combined	Two or more substances physically mixed
Ratio	Fixed	Fixed	Variable
Properties	Same as atoms	New properties formed	Components retain properties
Separation	Not possible	Only by chemical methods	By physical methods

Example: Oxygen (element), Water (compound), Air (mixture). hecu108

3. Describe the experiment of iron filings and sulfur and explain how it shows the difference between mixture and compound.

Answer:
When iron filings and sulfur powder are mixed, they form a mixture. Iron can be separated using a magnet because it retains its magnetic property.

When this mixture is heated, a new substance called iron sulfide is formed.

Differences observed:

• Iron sulfide has new properties different from iron and sulfur.
• Iron cannot be separated by a magnet.
• The compound is formed by chemical reaction.

Thus, this experiment clearly shows the difference between a mixture and a compound. hecu108

4. What are alloys? Explain why alloys are useful with examples.

Answer:
Alloys are mixtures of two or more metals or a metal with a non-metal. They are made to improve the properties of metals.

Uses and Advantages:

• Stronger than pure metals
• More resistant to rust and corrosion
• Better durability

Examples:

• Brass (copper + zinc)
• Stainless steel (iron + carbon + chromium)
• Bronze (copper + tin)

Alloys are widely used in utensils, machinery, and construction. hecu108

5. Explain why air is considered a mixture and not a compound.

Answer:
Air is a mixture because it contains several gases such as nitrogen, oxygen, carbon dioxide, and water vapour.

Air is not a compound because:

• Gases are not chemically combined.
• The proportion of gases can vary.
• Each gas retains its own properties.
• Components can be separated physically.

Thus, air is a uniform mixture essential for life on Earth