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Q1. Which of the following is not a physical change?

• Inflating a balloon
• Breaking glass
• Hammering wood
• Burning gasoline in car

Solution

In a chemical change, new substances are formed and burning of gasoline results in the  formation of new products with different properties.

Q2. Which of the following change can be reversed?

• Ripening of fruits
• Digestion of food
• Breaking of bone
• Souring of milk

Solution

Breaking of bone is a physical change that can be reversed.

Q3. What type of change is writing on paper?

• Chemical change
• Physical change
• Both chemical and physical change
• No change

Solution

In a physical change, the chemical properties of substances do not change.

Q4. What type of change is involved in melting of copper metal?

• Change in chemical properties of metal
• Change in shape of the metal
• Increase or decrease in temperature
• Change in physical properties of metal

Solution

In a physical change, the chemical properties of substances do not change.

Q5. Regular coating of paint prevents iron articles from

• Rusting
• Oiling
• Dusting
• Getting faded

Solution

Regular coating of paint prevents iron articles from rusting.

Q6. Slow oxidation of iron to form hydrated iron oxide is called:

• Rusting
• Galvanising
• Rust proofing
• Dip plating

Solution

Slow oxidation of iron to form hydrated iron (III) oxide is called rusting. 

Q7. Which of the following is not a physical change?

• Crushing of  a cola can 
• Breaking a piece of chalk to form small pieces 
• Melting of ice to form water  
• Rusting of iron 

Solution

Rusting of iron is a chemical change since it cannot be reversed.

Q8. Rusting can be prevented by:

• Painting the iron article
• Heating the iron article
• Storing the iron article in the soil
• Storing the iron article in the almirah

Solution

Rusting can be prevented by painting the iron article. This will stop the contact of the article with air and moisture present in the air.

Q9. During a physical change, which properties undergo change?

• Physical properties
• Chemical properties
• Both physical and chemical properties
• No change

Solution

Changes in which only physical properties of a substance undergo change are called physical changes.

Q10. Which of the following exhibits physical change?

• Melting of silver
• Water absorbed in a paper towel
• Mixing chalk powder in water
• All the above

Solution

Physical changes are generally reversible changes in the physical properties of substances. No new substances are formed in these changes.

Q11. In galvanisation, the iron metal is coated with which metal to prevent rusting?

• Copper
• Sodium
• Zinc
• Gold

Solution

In the process of galvanisation, the iron metal is coated with zinc to prevent rusting.

Q12. Imagine you want to eat pop-corn. You heat corn seeds in a pan. What type of change is this?

• Chemical change
• Physical change
• Crystallisation
• All of the above

Solution

Heating changes the chemical properties of corn and thus it is a chemical change.

Q13. Which of the following is NOT a physical change?

• Tearing postcard
• Making curd
• Melting wax
• Mixing oil in water

Solution

Curd is made from soured milk which is a chemical change.

Q14. Stainless steel is an alloy of iron with:

• Zinc
• Aluminium
• Chromium and nickel
• Chromium and copper

Solution

Stainless steel is an alloy of iron with chromium and nickel.

Q15. Name the change involved in boiling water to make pasta.

• Chemical change
• Physical change
• Condensation
• Evaporation

Solution

During a physical change, no new substance is formed. The process of boiling does not involve formation of any new substance.

Q16. Which of the following is a physical change?

• Sharpening a pencil
• Tearing paper
• Handpicking
• All the above

Solution

Physical changes are reversible changes. No new substances are formed in these changes.

Q17. Select the process associated with chemical change.

• Change in colour
• Formation of new products
• Release of heat and light
• All the above

Solution

In addition to new products, the following may accompany a chemical change - emitting or absorbing heat, light or any other radiation, producing sound, change in smell may take place or a new smell may be given off, colour change may take place or gas may be formed.

Q18. How are tools and machine parts made of iron protected from rusting?

• Applying grease on it
• Heating the articles
• Storing the articles at low temperature
• Coating the articles with zinc

Solution

Rusting of tools and machine parts can be prevented by applying a coat of grease or oil on it. This will stop the contact of the articles with air and moisture present in the air.

Q19. Select a chemical change happening from the given examples.

• Breaking of glass
• Washing of grains
• Baking a cake
• Sugar solution

Solution

In a chemical change, new substances are formed.

Q20. Name the change involved in the burning of coal in blast furnace.

• Irreversible physical change
• Reversible physical change
• Chemical change
• Physical at low temperatures and chemical at high temperatures

Solution

Coal burns to produce carbon dioxide, water, ashes and energy. A change in which new substances are formed is called a chemical change.

Q21. Which of the following is a physical change?

• Burning of fire crackers
• Boiling of water
• Cooking of food
• Ripening of fruits

Solution

Boiling of water is a physical change since it only involves a change in state. There is no new compound formed.

Q22. Crystallisation of sugar is an example of:

• Physical change
• Chemical change
• Evaporation
• Condensation

Solution

Crystallisation is formation of large crystals of pure substances from their solution. It is an example of physical change.

Q23. Breaking of ozone to form oxygen is an example of which change?

• Chemical change
• Physical change
• Crystallisation
• Both chemical and physical change

Solution

A change in which new substances are formed is called a chemical change.

Q24. Magnesium oxide is:

• White powder
• Black powder
• White gas
• Black gas

Solution

Magnesium oxide is a white powder.

Q25. Which of the following increases the rate of rusting?

• Dry air
• Hydrogen
• Salts
• Nitrogen

Solution

The presence of salts in water increases the rate of rusting.

Q26. Burning of a substance is an example of:

• Physical change
• Chemical change
• Incomplete chemical change
• Both physical and chemical change

Solution

In a chemical change, new substances are formed. Burning of a substance involves formation of new products.

Q27. Rust is:

• same in composition as iron
• different in composition from iron
• sometimes same composition and sometimes different composition as iron
• a process and not a compound

Solution

Rust is different in composition from iron.

Q28. Which of the following is not a physical change?

• Crushing a cola can
• Breaking a piece of chalk to form small pieces
• Melting of ice to form water
• Rusting of iron

Solution

Rusting of iron is a chemical change.

Q29. For making potato fries, you slice the potatoes (process 1) and deep fry it in oil (process 2). What type of changes are the two processes?

• Process A - Chemical change, Process B - Physical change
• Process A - No change, Process B - Physical change
• Process A - Physical change, Process B - Chemical change
• Process A - Chemical change, Process B - Chemical change

Solution

During a physical change, no new substance is formed whereas in a chemical change, new substance is formed with new chemical composition and properties.

Q30. Identify the chemical change.

• Cutting of a log of wood.
• Stretching of metals to form wires.
• Formation of clouds.
• Formation of manure.

Solution

Formation of manure from leaves is a chemical change since it involves the formation of a new product with different properties.

Q31. Which of the following cannot be called a physical change?

• Grating cheese
• Fermenting of cheese
• Melting cheese
• Mixing two cheeses in a bowl

Solution

Fermenting of cheese is a chemical change.

Q32. Surgical instruments do not rust as they are made of:

• Iron mixed with Zinc
• Iron mixed with lead
• Iron mixed with copper
• Iron mixed with nickel

Solution

Surgical instruments do not rust at all since they are made of iron mixed with nickel. This forms the stainless steel alloy.

Q33. Magnesium burns in oxygen to form:

• Magnesium oxide
• Magnesium hydride
• Magnesium hydroxide
• Magnesium carbonate

Solution

Magnesium burns in oxygen to form magnesium oxide.

Q34. Select the change in which chemical properties does not change.

• Physical Change
• Chemical Change
• Both physical and chemical change
• Chemical reaction

Solution

In a physical change, the chemical properties of the  substances do not change.

Q35. Metal that can be deposited on iron to prevent rusting is/are:

• Chromium
• Zinc
• Both A and B
• None of these

Solution

Both chromium and zinc can be deposited on iron to prevent rusting.

Q36. The necessary condition for rusting of iron is:

• Oxygen only
• Moisture only
• Both Oxygen and moisture
• Sodium chloride

Solution

The necessary condition for rusting of iron to occur is that it requires both oxygen and moisture.

Q37. The iron pipes used in homes to carry water are coated with:

• Zinc
• Aluminium
• Copper
• Plastics

Solution

The iron pipes used in homes to carry water are coated with Zinc to prevent rusting.

Q38. Select the statement that holds true for a chemical change.

• The original substance can be obtained back.
• Formation of new products.
• Only color change observed in the products formed.
• No energy released.

Solution

In addition to new products, the following may accompany a chemical change - emitting or absorbing heat, colour change may take place or a gas may be formed.

Q39. Chemically rust is:

Solution

Chemically rust is hydrated iron (III) oxide (Fe₂O₃.xH₂O)

Q40. Neutralisation of calcium hydroxide with hydrochloric acid is an example of:

• Chemical change
• Physical change
• Both chemical and physical change
• No change