SETH ANANDRAM JAIPURIA SCHOOL VASUNDHARA,GHAZIABAD OLYMPIAD WORKSHEET CLASS VI SCIENCE TOPIC: Changes Around Us

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1 SETH ANANDRAM JAIPURIA SCHOOL VASUNDHARA,GHAZIABAD OLYMPIAD WORKSHEET CLASS VI SCIENCE TOPIC: Changes Around Us 1. What is the common among the following phenomena? 1. Blinking of eyes. 2. Rotation of blades of a fan. 3. Swinging of pendulum of a clock. All are chemical changes. All are undesirable changes. All are periodic changes. All are irreversible changes. 2. Which of these is not a physical change? Dissolution of sulphur in carbon disulphide. Fermentation of cane juice. Dissolution of resin in alchol. Glowing of an electric bulb. 3. Tony is magnetizing a needle. This is a change. Chemical, irreversible. Physical, reversible. Chemical, reversible. Physical, irreversible. 4. A change in which heat is liberated is a change. Exothermic Periodic Physical Endothermic 5. Which of the following changes results in the formation of a new substance? Physical Reversible Chemical Periodic 6. Exchange of energy takes place in a physical change. No Some More Any of these 7. A change that is useful to man is change. Irreversible Chemical Desirable Periodic 8. Physical changes do not effect the of the substance.

2 Appearance Colour Chemical properties Size 9. Which of these is a slow, natural and irreversible change? Steel made from raw iron A baby grows to man Changing of milk into curd Burning of paper. 10. A potter shapes pots out of clay and then bakes them in a furnace identify the irreversible change taking place in the process Shaping the pots out of clay Both shaping and baking the pots Baking the pots in the furnace None of these 11. In which of the following cases heat energy is given out? When water boils When water freezes to ice When ice melts When water vapor is condenses to water 12. When ice melts, it forms water. When water boils, it forms steam. Ice, water and steam have very different properties, still these changes are considered as physical changes. The possible reason for this is A physical change involves the formation of substances with different properties. There is no difference in the chemical composition of ice, water and steam, only physical state is different. There is no difference in the taste of steam, ice and water hence it is a physical change There is no difference is colour of steam, ice and water hence it is a physical change. 13. Mark the incorrect statement. Melting of wax is a physical change while burning of wax in a candle is a chemical change. Metals expand on heating while contract on cooling. Both are physical changes. Composition of matter changes during a chemical change while it remains same during a physical change. High and low tides in sea are the examples of non - periodic changes while growth of a tree is a periodic change.

3 14. Select the appropriate option by observing the figures in which Ritika boiled a few potatoes and cut them into small pieces. Boil Cut Raw potatoes Boiled potatoes Pieces of boiled potatoes (P) (Q) (R) P Q : Physical change, Q R : Chemical change P Q : Physical change, Q R : Physical change P Q : Chemical change, Q R : Chemical change P Q : Chemical change, Q R : Physical change 15. Sudha took lemon juice in two flasks. She put salt in flask I and washing soda in flask II. She observed lots of bubbles in flask II but nothing in flask I. What could be the reason for this? In flask I, a chemical change takes place. In flask II, a chemical change takes place and bubbles of carbon dioxide are seen In flask II, a physical change takes place producing lots of bubbles. In flask I, salt reacts with lemon juice and forms a new compound. 16. Nitu mixed some iron filings with sulphur powder in a China dish. She heated the contents of a China dish. What did she observe during the experiment? There was no difference in the contents of China dish before and after heating. Before heating, iron filing and sulphur powder could be seen separately but after heating the contents became black. Before heating, the iron filings and sulphur powder could not be seen separately. Before heating, the contents were black and after heating iron filing and sulphur could be seen separately. 17. What kind of change is the making of a ring from pure gold? An irreversible, chemical change. An irreversible, physical change. A reversible, chemical change. A reversible, physical change.

4 18. A metallic piece X is dropped into copper sulphate solution after sometime the blue color of the solution changes to green the change which is occurred is Physical and reversible change Physical and irreversible change Chemical and reversible change Chemical and irreversible change 19. Given below is a change that occurs in butter: Butter (Solid state) X Y Butter (Liquid state) Identify X and Y that causes change in state of butter. X Heat lost, Y Heat gain. X Heat gain, Y Heat lost. X Release of energy, Y Absorption of Energy. X Decrease in temperature, Y Increase in temperature. 20. Study the given flowchart carefully. Changes P Q (i) Melting of ice. (i) Burning of paper. (ii) Blowing of a ballon. (ii) Flowering of bud. Which of the following is correct? (P) (Q) Reversible change Reversible change Irreversible change Reversible change Irreversible change Irreversible change Reversible change Irreversible change

5 21. Identify an undesirable changes from the following. Ripening of fruits. Occurrence of earthquakes. Preparing starch by photosynthesis in plants. Evaporation of sea water. 22. Identify the chemical change from the following. Heating of sugar. Dissolution of sugar in water. Crystallization of sugar. Powdering of sugar. 23. Select the statement which is true. All non periodic changes are not desirable. Desirable changes are temporary. Non desirable changes can cause damage. All natural changes are desirable. 24. Read the given statements and select the correct option. Statement 1 : Breaking of a glass tumbler is an irreversible physical change. Statement 2: When a glass tumbler breaks, the chemical composition of glass does not change but the pieces cannot be joined back to get original tumbler. Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1. Both statements 1 and 2 are true and statement 2 is not the correct explanation of statement 1. Statement 1 is true and statement 2 is false. Both statements 1 and 2 are false. 25. Select the statement which is not true. Rust is a completely new substance. Rusting occurs when iron is exposed to moisture. It is yellowish brown in colour. It cannot be changed back to iron.

I. Tick ( ) the most appropriate answer. 1. Physical or chemical changes are a result of absorption of :

4 CHANGES AROUND US I. Tick ( ) the most appropriate answer. 1. Physical or chemical changes are a result of absorption of : (a) heat energy only (b) light energy only (c) sound energy only (d) some kind