SEBA Class 7 Science Chapter 1 Physical and Chemical Changes Around Us

SEBA Class 7 Science Chapter 1 Physical and Chemical Changes Around Us Solutions English Medium As Per SCERT New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters SEBA Class 7 Science Chapter 1 Physical and Chemical Changes Around Us Notes and select need one. SEBA Class 7 Science Textual Notes Download PDF. SCERT Class 7 Science New Textbook Question Answer in English.

SEBA Class 7 Science Chapter 1 Physical and Chemical Changes Around Us

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Physical and Chemical Changes Around Us

Chapter: 1

PART – I

EXERCISES

1. Darken the circle of the correct answer.

(i) Which of the following is an example of a physical change?

(a) Burning of wood.

(b) Rusting of iron.

(c) Melting of ice.

(d) Milk turning sour.

Ans: (c) Melting of ice.

(ii) Which of the following shows a chemical change?

(a) Stretching a rubber band.

(b) Boiling of water.

(c) Burning of magnesium ribbon.

(d) Cutting paper into pieces.

Ans: (c) Burning of magnesium ribbon.

(iii) Which of the following changes cannot be reversed?

(a) Freezing of water.

(b) Dissolving sugar in water.

(c) Boiling of water.

(d) Burning of paper.

Ans: (d) Burning of paper.

(iv) Which of the following can prevent or slow down rusting of iron objects?

(a) Storing in a humid place.

(b) Painting or oiling the surface.

(c) Washing with water often.

(d) Exposing to rain.

Ans: (b) Painting or oiling the surface.

2. Which of the following statements are the characteristics of a chemical change?

(i) New substances are formed.

(ii) No new substance is formed.

(iii) It is usually irreversible.

(iv) Only the state of matter changes.

(a) (i) and (iii)

(b) (ii) and (iv)

(c) (i) and (ii)

(d) (iii) and (iv)

Ans: Ans: (a) (i) and (iii). 

Reasoning: A chemical change is defined by the formation of one or more new substances through a chemical reaction. These changes are generally permanent and irreversible in nature.

3. Which of the following changes can be reversed and which cannot be.

(a) Melting of ice cubes.

Ans: Reversible.

(b) Burning of paper.

Ans: Irreversible.

(c) Inflating a balloon.

Ans: Reversible.

(d) Digestion of food.

Ans: Irreversible.

(e) Evaporation of water from wet clothes.

Ans: Reversible.

(f) Rusting of iron.

Ans: Irreversible.

(g) Stretching of a rubber band.

Ans: Reversible.

(h) Baking a cake.

Ans: Irreversible.

(i) Sharpening a pencil.

Ans: Irreversible.

(j) Freezing water to make ice.

Ans: Reversible.

4. State whether the followings are True or False. Correct the false one.

(a) Freezing of water is a chemical change.

Ans: False. 

Correction: Freezing of water is a physical change because the material (water) remains fundamentally unchanged and can be reversed.

(b) Burning of wood produces new substances like ash, carbon dioxide, and water vapour.

Ans: True. Burning of wood (combustion) is a chemical change that creates new substances.

(c) Tearing of paper is a physical change.

Ans: True. Tearing paper into pieces only changes its size and shape, not the material itself.

(d) Boiling water to form steam is a chemical change.

Ans: False. 

Correction: Boiling water to form steam is a physical change because it is a change of state (liquid to gas) and no new substance is formed.