CBSE Class 7 Science The World of Metals and Non metals (Class 7 NCERT New) Quiz 2

1. Iron objects often develop brown deposits when left in the open. Under which condition does an iron object develop these brown deposits?

A When it comes into contact with dry air only B When it comes into contact with water only C When it comes into contact with both air and water D When it is kept away from both air and water

2. In an experiment with three stoppered glass bottles each containing an iron nail, bottle A has dry air (with silica gel), bottle B has water covered with a thin oil layer, and bottle C has both air and water in contact with the nail. After several days, what conclusion can be drawn about the formation of brown deposits on iron?

A Brown deposits form only in dry air B Brown deposits form only in water without air C Brown deposits form when both air and water are present; moist air causes rusting D Brown deposits never form on iron

3. Activity 4.6: A clean magnesium ribbon (about 3–4 cm) is ignited and allowed to burn (see image of a glowing strip held with tongs over a flame). What should you observe during burning?

A A dim red glow forms and the ribbon melts into tiny droplets B It burns with a dazzling white flame and leaves a white powder on the watch glass C The ribbon turns brown without any flame and becomes a brittle strip D Thick black smoke is produced and the ribbon swells into a sponge-like mass

4. Activity 4.6: The white powder collected after burning magnesium ribbon is mixed with warm water and stirred. What is the nature of the resulting solution?

A Acidic in nature B Basic in nature C Neutral in nature D Salty but neither acidic nor basic

5. Activity 4.7: Powdered sulfur is burned in a deflagrating spoon and the spoon is introduced into a covered gas jar; after a few minutes, water is added and the jar is shaken to dissolve the gas. What is the nature of the resulting solution?

A Acidic in nature B Basic in nature C Neutral in nature D Amphoteric in nature

6. Activity 4.7: After dissolving the gas formed by burning sulfur in water, how will the solution affect litmus papers?

A Turns blue litmus red and leaves red litmus unchanged B Turns red litmus blue and leaves blue litmus unchanged C Turns both blue and red litmus papers purple D Has no effect on either blue or red litmus papers

7. Does sulfur behave in water the same way metals do?

A Yes, it reacts with water like many metals B No, it does not react with water as metals often do

8. Activity 4.8: Sulfur powder is placed in a glass tumbler and a small amount of water is added. What do you observe?

A No reaction occurs when sulfur is placed in water B Sulfur dissolves readily to form a yellow solution C Bubbles of hydrogen gas are produced vigorously D A basic solution forms that turns red litmus blue

9. Which metal is commonly used to make food packaging materials as it is cheaper, and its thin sheets can be folded easily into any shape?

A Aluminium B Copper C Iron D Gold

10. Which of the following metal catches fire when it comes in contact with water?

A Copper B Aluminium C Zinc D Sodium