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• Class 7 Chemistry Worksheet on Chapter 6 Physical and Chemical Changes Set 1

Chemistry Worksheets Class 7 on Chapter 6 Physical and Chemical Changes with Answers - Set 1

The changes around us may involve changes in shape, size, position, colour, temperature, structure, composition, and state. These changes affect substances. Stretching a rubber band, burning a candle, cooking food, settling curd, and dissolving sugar in water are a few of the changes. These changes are broadly classified into two types- physical changes and chemical changes.

A change in which the physical property of substance changes and no new substance is formed is known as a physical change. Example: Melting of ice, cutting of trees, tearing of paper, etc. In contrast, a change in which two substances interact to produce one or more new substances with different properties is known as a chemical change. Example: Rusting of iron, formation of manure from leaves, formation of curd from milk.

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CBSE Class 7 Chemistry Chapter 6 Physical and Chemical Changes Worksheet – Set 1

Q1. Rusting of iron is a _______.

(a) Physical change

(b) Chemical change

(c) Both (a) and (b)

(d) Neither (a) nor (b)

Q2. What happens when sulphur is heated with iron fillings?

(a) Fast change

(b) Physical change

(c) Periodic change

(d) None of the above

Q3. What is the chemical formula of rust?

(a) Iron sulphide

(b) Iron oxide

(c) Iron hydroxide

Q4. Souring of milk is an example of _______.

(c) Natural change

Q5. Growth of plants is ________.

Q6. The reddish-brown layer deposited on the surface of iron objects is called ________.

Q7. A _______ change is also known as a chemical reaction.

Q8. The chemical formula of magnesium oxide is _______.

Q9. State true or false.

Cutting a log of wood is a chemical change.

Q10. State true or false.

The formation of manure from leaves is a physical change.

Q11. What are the constituents of stainless steel?

Q12. What is a chemical change?

Q13. What is rusting?

Q14. What is galvanisation?

Q15. What is crystallisation?

Q16. Distinguish between a physical and chemical change.

Q17. State any three ways of preventing rusting of iron.

Q18. What is a physical change? State any four characteristics of physical change with examples.

Q19. What happens if the gas produced by the reaction between vinegar and baking soda is passed through limewater? Justify your answer.

Q20. Why do you observe a change in colour of the solutions of copper sulphate when an iron nail is dropped in it? Why does the shining iron nail become dull?

Download the PDF to access answers to the Chemistry Worksheet for Class 7 Chemistry Chapter 6 Physical and Chemical Changes Set -1 Download PDF

• Chemical and Physical Change
• Difference Between Physical and Chemical Change
• Chemical and Physical Change Examples
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Class 7 science worksheet-6.

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Sep 29, 2022, 16:45 IST

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Science - Class 7 (C ...

Science - class 7 (chapter 01-10), topic outline, chapter 6 - physical and chemical changes - 1.

Physical and Chemical Changes

Q1. fill in the blanks..

                            i.         Cutting a log of wood into pieces is a physical change.

                           ii.         Condensation is a physical change.

                          iii.         When carbon dioxide is passed through lime water, it turns milky due to the formation of Calcium Carbonate .

                          iv.         Two methods by which rusting of iron can be prevented are painting or greasing and galvanisation .

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

                        vi.         A medicine is the end product of a chain of chemical reactions .

Q2. True/False

                            i.         Formation of manure from leaves is a physical change. False

                           ii.         Iron pipes coated with zinc do not get rusted easily. True

                          iii.         Iron and rust are the same substances. False

                          iv.         The chemical name of baking soda is Sodium hydrogencarbonate. True

                           v.         Changes in which new substances are formed are called chemical changes. True

Q3. What type of change is crystallisation?

Ans. It is a physical change.

Q4. What type of change is involved in rusting of iron?

Ans.  Rusting of iron is a chemical change.

Q5. Write one property of stainless steel.

Ans. It does not rust.

Q6. What type of change is formation of manure?

Ans. Formation of manure is a chemical change.

Q7. Which of the two is permanent change chemical change or physical change?

Ans. Chemical change is a permanent change.

Q8. What do you understand by chemical change?

Ans. A change in which one or more new substances are formed is called a chemical change.

Q9. State the conditions necessary for rusting of iron?

Ans. For rusting, the presence of both oxygen and water (or water vapour) is essential.

Q10. What is galvanisation?

Ans. The process of depositing a layer of metal like zinc or chromium on iron is called galvanisation.

Q11. What is added to steel to make it stainless?

Ans. Stainless steel is made by mixing iron with carbon and metals like chromium, nickel and manganese.

Q12. Why formation of manure from leaves is a chemical change?

Ans. Formation of manure from leaves is a chemical change because manure formed has a different composition from leaves.

Q13. Why souring of milk is a chemical change?

Ans. Souring of milk is a chemical change because it results in formation of new substance.

Q14. What is rust?

Ans. If a piece of iron is left in the open for some time, it acquires a film of brownish substance. This substance is called rust.

Q15. What is blue vitriol?

Ans. Crystals of copper sulphate pentahydrate are blue in colour. So, it is commonly known as blue vitriol.

Q16. Name the two methods by which rusting of iron can be prevented.

Ans. Two methods by which rusting of iron can be prevented are by painting or greasing and by galvanizing.

Q17. What happens when baking soda is treated with vinegar?

Ans. Vinegar (Acetic acid) + Baking soda (Sodium hydrogencarbonate) → Carbon dioxide + other substances

Q18. Which technique is better for obtaining sugar from sugar solution?

Ans. Crystallization is considered as a better technique for obtaining sugar from sugar solution.

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CBSE Class 7 Science - Physical and chemical changes - Worksheet #6

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CBSE Class 7 Science Physical and Chemical Changes Worksheet

CBSE Class 7 Science Physical and Chemical Changes Worksheet with Solution by Expert Science Mam. Students of 7th Grade can solve this worksheet for extra preparation before exam. Private Teacher or Guardians of the Students can copy all the questions of this chapter and will match after solve their students.

Physical and Chemical Changes Class 7 Worksheet

Worksheet for Chapter No.6): – Physical and Chemical Changes

The following questions are important for your exams for 1 mark 2 mark or 5 marks. First solve the questions on your own and then saw the solution for understanding it better.

Practice worksheet for class 7

Q.1.) Define physical change ? Give one example?

→   A change in which substance undergoes a change in its physical properties   is called as a physical change.

E.g., ice is converted into water.

Q.2.) What is chemical change ? Give one example?

→   A change in which a substance undergoes a change in its chemical properties called as chemical change. A change in which one or more new substances are formed called as chemical change.

E.g., rusting of iron.

Q.3.) What is chemical reaction give some examples?

→   Reaction in which one or more reactance reacts to produce one or more products is called as Chemical reaction.

Example:- digestion of food in our body, ripening of fruits, fermentation of grapes.

Q.4.) Who protects Earth from harmful radiation of the Sun? And how?

→   Ozone layer protects Earth from the harmful ultraviolet radiation which are coming from the Sun. Ozone absorb this radiation and breaks down to oxygen.

Q.5.) Who’s presence essential for rusting to happen?

→ The presence of both Oxygen and water is essential for rusting to happen.

Q.6.) Define crystallization? Give example?

→ Crystallization is the physical change in which large crystals of pure substances can be formed from their solution.

E.g., formation of salt by the evaporation of seawater.

Q.7.) What is galvanization ?

→ Galvanization is the process of depositing a layer of zinc on iron to prevent its corrosion or rusting of iron.

Q.8.) Classify the following changes as a physical or chemical changes?

→ 1.) Melting of ice – physical change

2.) Photosynthesis – chemical change

3.) Digestion of food :- chemical change

4.) Formation of Salt from seawater – physical change

5.) Rusting of iron – chemical change.

Q.9.) Write the two methods by which rusting of iron can be prevented ?

→ 1.) Galvanization

2.) By painting the piece of iron.

Q.10.) Why rusting of iron is faster at coastal regions than in the desert region?

→ 1.) At coastal regions,  there is presence of a lot of moisture along with the oxygen around the region. Therefore, resting of iron is faster at coastal regions due to presence of moisture and oxygen.

2.) In case of desert region, there is presence of oxygen but lack of moisture and hence there is slower the rate of rusting of iron than in the coastal region.

Q.11.) Which gas is formed in the reaction of vinegar with baking soda ?

→   In the reaction of vinegar and baking soda , the carbon dioxide is get formed.

Q.12.) What will happen when carbon dioxide and lime water react together?

→  Carbon dioxide (CO 2 ) + Lime Water [Ca(OH) 2 ] → Calcium Carbonate

(CaCO 3 ) + Water (H 2 O).

Q .13.)  What happen when a cut apple is kept for open for a long period of time? Which kind of change it was ?

→ 1.) When we cut apple into pieces and kept it in the air exposed to oxygen and moisture  for a long period of time it will turn brown in color due to the oxidation process .

2.) This is a type of chemical change.

Q.14.) Why brinjal and potatoes turn brown after cutting ?

→ 1.) Brinjal and potatoes contain polyphenol oxidase enzyme in it.

2.) When they are cut open and exposed to atmospheric Oxygen and moisture it will turn brown due to the oxidation process.

Q.15.)  What happens when magnesium and oxygen react together ?

→    When magnesium and oxygen react together the magnesium oxide is get formed in the form of powdery Ash.

Magnesium (Mg) + Oxygen  (O 2 ) → Magnesium oxide (MgO)

Q.16.) What is the nature of the product of reaction between magnesium oxide and water ? Which litmus paper shows the nature of the product ?

→ Magnesium oxide (MgO) + Water (H 2 O) → Magnesium hydroxide

[Mg(OH) 2 ]

In above reaction magnesium hydroxide is get formed. Magnesium hydroxide is a base hence red litmus paper turns blue in color.

Q.17.) Why there is a change in color from Blue to green between the reaction of copper sulphate and iron needle?

→  Copper sulphate solution ( blue) + Iron → Iron sulphate solution

(green) + Copper (brown deposit)

There is a change of colour from Blue to green due to formation of iron sulphate solution. When copper sulphate solution which is blue in colour reacts with iron it will form I am sulphate solution and copper is deposited on the iron needle and it becomes brown in colour.

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