Materials: Metals and Non-Metals Quiz - CBSE Class 8 Science

Free practice quiz: Materials: Metals and Non-Metals (CBSE Class 8 Science). 12 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. Which of the following is a characteristic of most metals?

   1. They are brittle and break easily.
   2. They are poor conductors of heat.
   3. They are dull and lack luster.
   4. They are good conductors of electricity.
   Show answer

   Answer: D. They are good conductors of electricity.

   Most metals are known for their excellent conductivity of electricity. This is due to the presence of freely moving electrons in their structure.

2. Which metal is known for its high reactivity with water?

   1. Gold
   2. Silver
   3. Copper
   4. Sodium
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   Answer: D. Sodium

   Sodium is an alkali metal that reacts vigorously with water, producing hydrogen gas and sodium hydroxide.

3. What is the process called where a metal is coated with a layer of zinc to prevent rusting?

   1. Electroplating
   2. Galvanization
   3. Alloying
   4. Painting
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   Answer: B. Galvanization

   Galvanization is a method of protecting steel and iron from rusting by coating it with a layer of zinc.

4. Describe a situation where the malleability of a metal is beneficial.

   1. Making electrical wires
   2. Building a bridge
   3. Manufacturing jewelry
   4. Constructing a building
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   Answer: C. Manufacturing jewelry

   Malleability, the ability to be hammered into shapes, is crucial in jewelry making. Metals can be easily shaped and formed into intricate designs.

5. Discuss the factors influencing the rate of corrosion of iron, considering both chemical and environmental aspects. Why is stainless steel more resistant?

   1. Higher purity iron corrodes slower; Stainless steel is an alloy with added chromium that forms a protective oxide layer.
   2. Lower purity iron corrodes slower; Stainless steel contains nickel which makes it less reactive.
   3. Higher purity iron corrodes faster; Stainless steel is a non-metal and therefore corrosion resistant.
   4. Lower purity iron corrodes faster; Stainless steel is a pure iron with a protective coating.
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   Answer: A. Higher purity iron corrodes slower; Stainless steel is an alloy with added chromium that forms a protective oxide layer.

   Corrosion depends on factors like oxygen and water availability, impurities in the metal, and pH of the environment. Stainless steel's chromium forms a passive oxide layer preventing further oxidation.

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