PSEB Class 6 Science Chapter 6 Changes Around Us Questions and Answers Solution
PSEB Punjab Board Class 6 Science Textbook Solution Chapter 6 Changes Around Us Exercise Questions and Answers. We have also included some Additional questions, so that students can prepare more strongly.
(1) Fill in the blanks: –
(a) A new substance is always formed in chemical change.
(b) Melting of ice is water and reversible change,
(c) Burning of paper is irreversible change.
(d) On heating metals expand.
(e) Change that is repeated after regular interval of time is known as periodic change.
(2) Write True or False: –
(a) Converting milk into paneer is a reversible change.
→False
(b) Rusting of iron is a slow change.
→True
(c) Metals contract on heating.
→False
(d) Melting of snow from hills is a natural change.
→True
(e) Burning of cracker is a fast change.
→True
(3) Match Column A with Column B.
→
A | B | |
a. | Freezing of water | Physical and reversible |
b. | Milk to curd | Chemical |
c. | Burning of matchstick | Fast |
d. | Earthquake | Non periodic |
e. | Change of season | Periodic |
(4) Choose the correct answer: –
(i) Cooking of food is which change:
(1) Physical (2) Fast
(3) Reversible (4) Irreversible
→(4) Irreversible
(ii) Which of the following change is non periodic?
(1) Heart beat
(2) Earthquake
(3) Occurrence of day and night
(4) Motion of pendulum
→(2) Earthquake
(iii) Which of the following expand on heating?
(1) Wood
(2) Paper
(3) Metal
(4) Cloth
→ (3) Metal
(iv) Rusting of irons is which type of change?
(1) Reversable
(2) Slow
(3) Perodic
(4) Fast
→ (2) Slow
(v) Growth in plants and animals is which type of change?
(1) Slow
(2) Reversable
(3) Chemical
(4) Periodic
→ (1) Slow
(5) Very short answer type questions: –
(i) What are changes?
→Changes, it is an act by which a thing becomes different from its previous.
Changes, is law of nature. Without change, life is not possible on the earth.
There are many types of changes in an around us.
(ii) Define slow and fast changes with examples?
→Slow changes are those which lakes more time to happen. i.e. growing of tree.
a baby becoming adult, etc. Fast changes are those that happen very fast. For
example, burning of match stick, bursting of crackers etc.
(iii) Give two examples of reversible change?
→Example: Ice changes to water on melting and water can be changed into ice by cooling. Is a reversible change.
(iv) Why iron rim is made slightly smaller than the wooden wheel?
→The metal rim used is slightly smaller in diameter than the wheels. On heating, the rim expands and can easily lie on the wheel. When the rim cools, it contracts and fits tightly onto the wooden wheel.
(v) Give two examples of chemical change?
→The incense stick gives pleasant smell and get reduced to ashes, candle give light in the dark and melting into wax it is a chemical change.
(6) Short answer type questions: –
(i) Give difference between periodic and non-periodic changes with examples?
→Periodic changes: – Changes that are repeated after regular interval of time are called periodic changes. Non-periodic changes: – Changes that are not repeated after regular interval of time are called non-periodic changes.
(ii) Give difference between reversible and irreversible changes with examples?
→Reversible changes: When a changes in a substance can be reversed by changing The conditions it is said to be reversible change. For example, ice changes to water by melting and water can be changed into ice by cooling.
Irreversible changes: If a substance after change cannot be brought back to its original state then the change is said to be an irreversible change. For example, roti (chapati) once prepared on tawa, cannot be changed back to dough again.
(iii) Why a candle reduces in size on burning?
→Candle reduces in size on burning because of, candle give light in the dark and melting into formation of wax it is anirreversible chemical change.
(iv) Give difference between physical and chemical with examples?
→Physical change is a temporary change in which no new substance is formed we can say that Physical change is a reversible change. For example, take some coloured clay and make any shape like toys, birds etc. aluminum foil paper.
Chemical change is a permanent change in which new substance are formed whose physical and chemical properties are completely different from those of the original substance we can say that chemical change is an irreversible change. For example, burning of incense stick and candles.
- (7) Long answer type questions: –
(i) What is expansion? Define thermal expansion. Explain with two examples?
→Expansion is the increase in the dimension of a body when subjected to high temperature and high pressure. Changes can be brought about by heating or colling certain substances. When expansion is due to increase in temperature it is called ‘thermal expansion.’ For example, blowing of balloon, stretching of spring, metals like iron, gold, silver soften on heating and can be molded into different shapes and sizes.Thus, on heating metals expand and on cooling they come back to their originalsize.
*EXTRA QUESTIONS AND ANSWERS
(1) Write down two examples of periodic changes?
→ Periodic changes are, (1) Beating of heart, and (2) Changes Day and night.
(2) Write down two examples of non-periodic changes?
→ Non-periodic changes are, (1) Earthquake, (2) Volcano, and non-seasonal raining etc.
(3) In which change the chemical composition of the substance remains same?
→ In ‘Physical change’ the chemical composition of the substance remains same.
(4) Name the change in which the chemical composition of the substance change?
→ In ‘Chemical change’ the chemical composition of the substance change.
(5) Name two examples of reversible change?
→ (1) Melting of ice into water, and (2) Stretching of rubber.
(6) Name two examples of irreversible change?
→ (1) Ripening of mango, and (2) Tearing of paper.
(7) Name the two metals which soften on heating?
→(1) Gold, and (2) Silver are metals which soften on heating.
(8) What do you mean by thermal expansion?
→The expansion when caused by increasing temperature is called as thermal expansion.
(9) What do you mean by contraction?
→The decrease in dimension of the body due to low temperature and high pressure is called as contraction.
(10) What do you mean by non-periodic changes?
→ Changes that are not arrived after a regular interval of time are called as non-periodic changes for example, earthquake and volcanoes.