The comprehensive approach in SCERT Class 6 Basic Science Textbook Solutions Chapter 7 The World of Changes Important Questions ensure conceptual clarity.
The World of Changes Extra Questions and Answers Class 6 Basic Science Chapter 7 Kerala Syllabus
The World of Changes Class 6 Important Questions
Question 1.
Different stages of the experiment related to state of change of water are given below.
A) Write any three findings of this experiment.
Answer:
- Ice absorbs heat energy and changes its state. It is converted into water.
- Water absorbs heat energy and changes its state. It is converted into water vapour.
- By absorbing heat energy, a substance changes its state to another state.
B) On the basis of this experiment, explain how rain is formed.
Answer:
By absorbing heat energy from the sun, the water is converted to water vapour and rises to the atmosphere, where this water vapour loses its heat energy and is converted back to water. This water drops down as rain.
Question 2.
Binu takes ice cubes in a beaker and heats it. He observed the changes that happened and recorded them.
(a) What happened to ice cubes in the beaker?
Answer:
Ice cubes changed into water
(b) Why?
Answer:
Ice cubes in the beaker absorb heat energy and change into water.
(c) Which form of energy was utilised by the ice to change?
Answer:
Heat energy
Question 3.
Science Fest is taking place at Anu’s School. Look at the materials collected for an experiment related to the changes of substances.
| wax, sugar, spirit lamp, salt, spoon, boiling tube, stand, water, beaker, test tube holder, wire gauze |
(A) Choose materials from the box to show chemical change and design an experiment.
Answer:
Materials required: Sugar, Spirit lamp, Spoon, Boiling tube, Test tube holder.
Experiment: Place a small amount of sugar in a spoon. Hold the spoon with the test tube holder. Carefully heat the spoon with the sugar using the spirit lamp. As you heat the sugar, observe any changes in colour, odour, or formation of gas.
Observation:
- The sugar will melt when heated.
- A brown or black-coloured liquid will form as the sugar decomposes.
- You might observe a caramel-like odour.
(B) Write two conclusions of this experiment.
Answer:
This experiment demonstrates a chemical change because:
- New substances are formed (brown liquid) from the original sugar and wax.
- The physical properties (colour, odour) of the starting materials differ from the final product.
- This is a permanent change.
Question 4.
Ramu and Thomu were studying physical and chemical changes. They burnt a piece of paper and concluded that it was a chemical change. Do you agree with them? State your answer.
Answer:
The burning of paper is a chemical change. After burning, a new substance is formed with new properties.
It is an irreversible change. After burning the paper, it cannot be unbumt. It is a permanent change.
Question 5.
Some of the situations in our daily life are given below.
- Curdling of milk
- Melting of wax
- Ripening of mangoes
- Tearing of paper
- Burning of firewood
- Boiling of water
(a) Classify them according to the peculiarities of the changes.
Answer:
| PHYSICAL CHANGE | CHEMICAL CHANGE |
|
|
(b) Write any two features of each change,
Answer:
| PHYSICAL CHANGE | CHEMICAL CHANGE |
|
|
Question 6.
Observe the illustration related to the change of state of water.
(a) Complete the illustration suitably.
Answer:
ii) Releases heat
iii) Releases Heat
iv) Absorbs heat
(b) The state of water having least heat energy.
Answer:
Ice
(c) Why food items can cook easily in steam than in boiled water?
Answer:
The state of water that has more heat energy than other sates is Steam. So food items can cook easily in steam.
Question 7.
A. Complete the table related to the various changes taking place in the kitchen.
| (i) | Chemical Changes |
| Ghee Melts | Milk turns to curd |
| (ii) | (iv) |
| (iii) | (v) |
Answer:
i) Physical Change
ii) Candle bums
iii) Cutting Vegetables
iv) LPG bums (cooking gas)
v) Paper bums/wood bums
B. Both chemical and physical changes are taking place while burning a candle.
Do you agree with this statement? Justify your answer.
Answer:
Wax undergoes both physical and chemical changes when a candle bums. The melting of the candle is a physical change. The wax near the wick melts from a solid to a liquid state while emitting heat and light. The burning of wax vapours is a chemical change.
Question 8.
Read the situations given below.
- Light crackers
- Operates the motor to draw water
- Operates the mixer grinder
- Bulb glows
- Lighting a matchstick
A) Tabulate the energy changes in each situation
| Situations | Energy Changes |
| _______________________ _______________________ Operates the mixer grinder _______________________ _______________________ |
_______________________ _______________________ Electrical Energy → Mechanical energy + Sound energy _______________________ _______________________ |
Answer:
| Situations | Energy Changes |
|
|
B) Group the situations in which the same energy change takes place
Answer:
Group 1 (Electrical → Mechanical)
- Operates the motor to draw water
- Operates the mixer grinder
Group 2 (Chemical → Light/ Heat/ Sound)
- Light crackers
- Lighting a matchstick
Question 9.
In festive seasons, we can see a variety of crackers bursting in temples and churches.
a) What are the energy forms produced here?
b) Which is the energy form that we make use of?
Answer:
a) Heat energy. Light energy, Sound energy
b) Light energy, Sound energy.
Question 10.
Examine the following situations.
A) In which situation mechanical energy is made use of?
Answer:
Working of a mixer grinder
B) Tabulate the energy changes in the given situations.
Answer:
| Situations | Energy changes |
| Bursting of a cracker | (a) Chemical Energy → (b) Light energy + (c) Sound Energy + Heat energy |
| Working of a mixer grinder | (d) Electrical Energy → Heat Energy + (e) Mechanical Energy + Sound Energy |
| Lighting a matchstick | (f) Chemical energy → (g) Sound energy + Heat + (h) Light Energy |