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Q1. Priya sees a sweet shop in Delhi where laddoos are covered with a very thin silver coating. Which property of silver allows it to be made into such a thin layer?
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Q2. A pressure cooker has a metal body but a wooden or plastic handle. The best reason for this design is
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Q3. An electrician uses a screwdriver with a plastic-covered handle and wears rubber gloves while working. The reason is that plastic and rubber are
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Q4. In Activity 4.5, three iron nails are placed: A — with silica gel (dry air only); B — under boiled water with an oil layer (water only, no air); C — partially in water, open bottle (water and air both). Where will brown deposit form?
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Q5. The Iron Pillar of Delhi is famous because
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Q6. Sulfur is burnt in air; the gas produced is dissolved in water. The resulting solution is
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Q7. Metal wires play an important role in stringed musical instruments such as veena, sitar, violin and guitar. Which property of metals makes this possible?
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Q8. Which non-metal is commonly used for water purification in our cities?
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Q9. Ropes made of steel wires are used in suspension bridges and in cranes because steel wires
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Q10. The ringing sound of a school bell and the sound of dancers' ghungroos are both produced because of
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Q11. Which of the following is NOT a method given in the chapter to prevent the rusting of iron?
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Q12. Sudarshan uncle heats an iron block in the furnace until it becomes red hot, then beats it with a hammer to shape it into an axe. Heating the iron first is necessary because heated iron
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Q13. A magnesium ribbon is burnt and the white powder is dissolved in warm water. Red litmus paper dipped in this solution will turn
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Q14. An old copper vessel left exposed in the open is observed to develop a green coating on its surface. This is an example of
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Q15. Plastic, wood, rubber and paper are NOT classified as metals or non-metals. The chapter gives the reason as
