CBSE Class 10 Chemistry Metals And Non Metals Worksheet Set 18

This printable CBSE Class 10 Science worksheet for Chapter 3, Metals and Non-metals, has 25 very short answer questions with answers. It covers physical properties of metals, abundant elements, and the reaction of metals with oxygen and water.

Very Short Answer Questions

Question 1. Why do metals become dull when exposed to air?
Answer:
A thin layer of oxide, carbonate or sulphide forms on the surface of the metal.
In simple words: The surface gets covered by a compound layer.

Teacher's Note:
1. Silver turns black and copper turns green in the same way.
2. Rubbing with sand paper restores the shine.

Question 2. What length of wire can be drawn from one gram of gold?
Answer:
About two kilometres.
In simple words: Gold is the most ductile metal.

Teacher's Note:
1. Ductility means drawing into wires.
2. Gold is also the most malleable metal along with silver.

Question 3. What is meant by thermal conductivity of metals?
Answer:
The ability of a metal to conduct heat through it is called its thermal conductivity.
In simple words: It is how well a metal carries heat.

Teacher's Note:
1. Silver and copper are the best conductors of heat.
2. Lead and mercury are poor conductors of heat.

Question 4. Arrange mercury, copper, tungsten and aluminium in decreasing order of electrical conductivity.
Answer:
Copper > aluminium > tungsten > mercury.
In simple words: Copper conducts best and mercury the least.

Teacher's Note:
1. Silver is the best conductor of all.
2. Aluminium is lighter than copper, so it is used in overhead cables.

Question 5. Explain the statement, 'Metals are sonorous'.
Answer:
Metals produce a ringing sound when they are struck by an object.
In simple words: Sonorous means that the metal rings when hit.

Teacher's Note:
1. School bells are made of metal for this reason.
2. Non-metals are not sonorous.

Question 6. Name a metal which offers higher resistance to the passage of electricity than copper.
Answer:
Mercury (lead and iron also have a higher resistance than copper).
In simple words: Mercury conducts worse than copper.

Teacher's Note:
1. Higher resistance means lower conductivity.
2. Copper and silver have the lowest resistance.

Question 7. Name two metals which are both very ductile and very malleable.
Answer:
Gold and silver.
In simple words: Gold and silver can be drawn into wires and beaten into sheets.

Teacher's Note:
1. Aluminium and copper are also malleable and ductile.
2. Silver foil is used to decorate sweets.

Question 8. Name some non-metals which are solid at room temperature.
Answer:
Carbon, sulphur, phosphorus and iodine.
In simple words: Many non-metals are solid at room temperature.

Teacher's Note:
1. Bromine is a liquid; oxygen and hydrogen are gases.
2. Iodine is a lustrous non-metal.

Question 9. Name the non-metal which is used in the hydrogenation of vegetable oils to make vegetable ghee.
Answer:
Hydrogen.
In simple words: Hydrogen is added to vegetable oils to make ghee.

Teacher's Note:
1. The process uses a nickel catalyst.
2. Hydrogen is a non-metal.

Question 10. Name the most abundant element in the earth's crust.
Answer:
Oxygen.
In simple words: Oxygen is the most plentiful element in the crust.

Teacher's Note:
1. Silicon comes second.
2. Aluminium is the most abundant metal.

Question 11. Name the second most abundant element in the earth's crust.
Answer:
Silicon.
In simple words: Silicon follows oxygen.

Teacher's Note:
1. Silicon is a metalloid.
2. Sand is silicon dioxide.

Question 12. Name the two most malleable metals.
Answer:
Gold and silver.
In simple words: They can be hammered into the thinnest sheets.

Teacher's Note:
1. Malleable means can be beaten into sheets.
2. Aluminium foil is also made by this property.

Question 13. Name one metal and one non-metal that exist in the liquid state at room temperature.
Answer:
Metal: mercury. Non-metal: bromine.
In simple words: Mercury and bromine are liquids at room temperature.

Teacher's Note:
1. Gallium and caesium melt just above room temperature.
2. All other metals are solids.

Question 14. A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.
Answer:
X is carbon, Y is diamond and Z is graphite.
In simple words: Diamond and graphite are two forms of carbon.

Teacher's Note:
1. Different forms of the same element are called allotropes.
2. Graphite is used for electrodes.

Question 15. What are alkalis? Give one example.
Answer:
Bases which are soluble in water are called alkalis. Sodium hydroxide, NaOH, is an example.
In simple words: Alkalis are water-soluble bases.

Teacher's Note:
1. Metal oxides like Na₂O give alkalis with water.
2. Alkalis turn red litmus blue.

Question 16. Name two amphoteric oxides.
Answer:
Aluminium oxide (Al₂O₃) and zinc oxide (ZnO).
In simple words: Amphoteric oxides react with both acids and bases.

Teacher's Note:
1. They are formed by Al and Zn.
2. They give a salt and water in both cases.

Question 17. What happens when magnesium is heated to its ignition temperature?
Answer:
It burns with a dazzling white flame to form white magnesium oxide: 2Mg + O₂ → 2MgO.
In simple words: Magnesium burns brightly and forms a white powder.

Teacher's Note:
1. Magnesium ribbon is cleaned before burning.
2. Do not look directly at the flame.

Question 18. What happens when iron is heated to a high temperature?
Answer:
Iron does not burn on heating; it only glows red hot. (Iron filings burn with sparks to form iron oxide.)
In simple words: Iron glows but does not burn as a piece.

Teacher's Note:
1. Fine powder burns more easily than a lump.
2. Rust is formed only with moisture.

Question 19. What happens when copper is heated to a very high temperature?
Answer:
Copper does not burn, but the hot metal is coated with a black layer of copper(II) oxide: 2Cu + O₂ → 2CuO.
In simple words: The surface of copper turns black.

Teacher's Note:
1. The black coating is CuO.
2. CuO is a basic oxide.

Question 20. What happens when metals react with water?
Answer:
Metals react with water to form a metal oxide or metal hydroxide and hydrogen gas.
In simple words: Metal + water gives metal hydroxide (or oxide) + hydrogen.

Teacher's Note:
1. Reactivity with water differs from metal to metal.
2. Sodium reacts violently, magnesium only with hot water.

Question 21. Name two metals that react violently with cold water.
Answer:
Potassium and sodium.
In simple words: They react violently and catch fire.

Teacher's Note:
1. The hydrogen released burns.
2. They are stored in kerosene.

Question 22. Write the chemical equation for the reaction taking place when a piece of calcium metal is placed in water.
Answer:
Ca + 2H₂O → Ca(OH)₂ + H₂
In simple words: Calcium gives calcium hydroxide and hydrogen.

Teacher's Note:
1. Calcium floats because hydrogen bubbles stick to it.
2. The reaction is less violent than sodium.

Question 23. Write the chemical equation for the reaction taking place when steam is passed over red hot iron.
Answer:
3Fe + 4H₂O → Fe₃O₄ + 4H₂
In simple words: Iron forms iron oxide Fe₃O₄ and hydrogen with steam.

Teacher's Note:
1. The oxide formed is not Fe₂O₄.
2. Check that O atoms are 4 on each side.

Question 24. A metal X on heating in air does not burn but acquires a black coating of a substance Y on its surface. Name the metal X and the substance Y.
Answer:
X is copper and Y is copper(II) oxide, CuO.
In simple words: Copper gets a black coating of CuO.

Teacher's Note:
1. The coating can be removed with hydrogen gas.
2. CuO is basic.

Question 25. In nature, metal P is found in the form of its compounds and metal Q is found in the free state. Which of the two will be nearer to the top of the activity series of metals?
Answer:
Metal P, because reactive metals combine with other elements while unreactive metals are found free.
In simple words: Metals found in compounds are more reactive.

Teacher's Note:
1. Gold and silver are found free.
2. Metals at the top are never free.