CBSE Class 7 Science The World of Metals and Non metals (Class 7 NCERT New) Quiz 4

1. What happens when oxygen reacts with magnesium and sulfur? Choose the option that correctly states the main differences in the nature of the products formed.

A Both reactions form basic oxides that turn red litmus blue B Magnesium forms a basic oxide while sulfur forms an acidic oxide C Both reactions form acidic oxides that turn blue litmus red D Magnesium and sulfur both form neutral oxides with no effect on litmus

2. Complete the flow chart: A solid is heated in air to form ash. The ash is mixed with water, and then blue and red litmus solutions are added separately. The blue litmus shows no change, and the red litmus turns blue. Which starting material best completes the chart?

A Magnesium ribbon B Sulfur powder C Charcoal D Copper turnings

3. You are provided with the materials iron, copper, sulfur, coal, plastic, wood, and cardboard. Which material would you choose to make a pan that is most suitable for boiling water, and why?

A Copper, because it conducts heat well and withstands high temperature B Plastic, because it is light and does not react with water C Wood, because it is a poor conductor and keeps the handle cool D Coal, because it burns to provide heat for boiling

4. Three iron nails are each dipped in oil, water, and vinegar. Which iron nail will not rust, and why?

A The nail in oil, because oil prevents contact with air and water B The nail in water, because pure water cannot corrode iron C The nail in vinegar, because acids remove oxygen from iron D All nails will rust at the same rate in any liquid

5. How do the different properties of metals and non-metals determine their uses in everyday life? Choose the most appropriate statement.

A Metals are used where thermal and electrical conductivity or strength is needed, while non-metals are chosen for insulation, chemical uses, and life processes B Non-metals are preferred for electrical wiring, while metals are used mainly for insulators and fertilizers C Both metals and non-metals are chosen randomly because their properties are similar D Metals and non-metals have no relation to their uses; cost alone decides applications

6. One method of protecting iron from rust is to put a thin coating of zinc metal over it. Since sulfur does not react with water, can it be used for this purpose?

A No, because galvanisation requires a zinc coating that provides sacrificial protection and adheres well, which sulfur cannot B Yes, sulfur is non-reactive with water and forms a protective layer like zinc C Yes, but only if the sulfur is mixed with oil before coating D No, because any coating other than paint will cause faster rusting

7. An ironsmith heats iron before making tools. Why is heating necessary in this process?

A Heating makes iron softer and more malleable so it can be hammered into shape B Heating makes iron a better conductor of electricity for tool use C Heating removes all carbon, turning the iron into pure copper D Heating changes iron into a non-metal that resists rust

8. Which of these is a property of metals?

A It's malleable B It can't conduct electricity C They are used in food D It's very brittle

9. What is just so typical of NON-metals?

A They don't know what colours go well together. B Malleable. C Form acidic oxides. D Good conductors of electricity. 5 High melting points.

10. A metal high in the reactivity series.....

A Forms unstable compounds. B Can be obtained by the reduction of the ore with the carbon. C Readily gains electrons. D Burns to form basic oxides. 5 Reacts readily with cold water to form Hydrogen.