CBSE Class 10 Chemistry Metals And Non Metals Worksheet Set 17

This printable CBSE Class 10 Science worksheet for Chapter 3, Metals and Non-metals, has 17 questions: true or false statements followed by very short answer questions, all with answers. The questions test the reactivity series, ionic compounds, extraction of metals, alloys and the prevention of corrosion.

True or False

Question 1. True or False: Electrovalent compounds conduct electricity in the solid state because ions are present in them.
Answer:
False. In the solid state the ions are held in fixed positions and cannot move. They conduct only when molten or dissolved in water.
In simple words: Ions must be free to move to carry current.

Teacher's Note:
1. Ionic solids are non-conductors.
2. Molten NaCl conducts electricity.

Question 2. True or False: The reaction that takes place in the aluminothermic process is called the thermite reaction.
Answer:
True. Aluminium reduces a metal oxide and a large amount of heat is produced, e.g. Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat.
In simple words: Aluminium reduces another metal oxide and gives heat.

Teacher's Note:
1. It is used to weld railway tracks.
2. Molten iron is produced.

Question 3. True or False: In the electrolytic refining of copper, pure copper is taken as the anode.
Answer:
False. Impure copper is the anode and pure copper is the cathode.
In simple words: Anode = impure, cathode = pure.

Teacher's Note:
1. Copper dissolves from the anode.
2. Anode mud collects below the anode.

Question 4. True or False: A more reactive metal displaces a less reactive metal from its salt solution.
Answer:
True. For example, zinc displaces copper from copper sulphate solution.
In simple words: The more reactive metal wins.

Teacher's Note:
1. Check the position in the reactivity series.
2. Zn + CuSO₄ → ZnSO₄ + Cu.

Question 5. True or False: The presence of carbon in pig iron makes it very soft and malleable.
Answer:
False. Carbon makes iron hard and brittle. Pure iron is soft and malleable.
In simple words: Carbon hardens iron.

Teacher's Note:
1. Steel is iron with a small amount of carbon.
2. Stainless steel contains Cr and Ni.

Very Short Answer Questions

Question 6. Name two metals which catch fire if kept in the open air.
Answer:
Sodium and potassium.
In simple words: Sodium and potassium burn in air.

Teacher's Note:
1. They are kept in kerosene.
2. Lithium also reacts.

Question 7. A metal X displaces a metal Y from an aqueous solution of Y₂(SO₄)₃. Which metal is more reactive, X or Y?
Answer:
X is more reactive than Y, because a more reactive metal displaces a less reactive one from its salt solution.
In simple words: The displacing metal is more reactive.

Teacher's Note:
1. This is a displacement reaction.
2. Reactivity series decides the direction.

Question 8. Name a non-metallic element which conducts electricity.
Answer:
Graphite (carbon) conducts electricity.
In simple words: Graphite conducts because of free electrons.

Teacher's Note:
1. It is used as electrodes.
2. Diamond does not conduct.

Question 9. What are metalloids?
Answer:
Elements that show properties of both metals and non-metals are called metalloids, e.g. silicon and germanium.
In simple words: Metalloids are in between metals and non-metals.

Teacher's Note:
1. They are semiconductors.
2. Arsenic is another metalloid.

Question 10. What is meant by galvanisation?
Answer:
Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of zinc.
In simple words: Zinc coating protects iron.

Teacher's Note:
1. Zinc is more reactive than iron.
2. Galvanised pipes are common.

Question 11. Define gangue.
Answer:
The impurities such as soil and sand present in an ore are called gangue.
In simple words: Gangue is the unwanted material in the ore.

Teacher's Note:
1. It is removed before extracting the metal.
2. Ore = metal compound + gangue.

Question 12. What is an amalgam?
Answer:
An alloy in which one of the components is mercury is called an amalgam.
In simple words: An amalgam is an alloy containing mercury.

Teacher's Note:
1. Used in dental fillings.
2. Mercury is a liquid metal.

Question 13. Which one of the following metals does not react with oxygen even at high temperatures: calcium, gold, sodium?
Answer:
Gold. It is very unreactive.
In simple words: Gold does not burn or tarnish.

Teacher's Note:
1. Sodium and calcium react readily.
2. Gold is a noble metal.

Question 14. Write the chemical equation for the reaction of hot aluminium with steam.
Answer:
2Al(s) + 3H₂O(g) → Al₂O₃(s) + 3H₂(g)
In simple words: Aluminium and steam give aluminium oxide and hydrogen.

Teacher's Note:
1. Metal + steam gives metal oxide + hydrogen.
2. Balance O and H atoms.

Question 15. Choose the metal from the following which can displace zinc from zinc sulphate solution: lead, copper, magnesium, silver. Write the equation.
Answer:
Magnesium, because it is more reactive than zinc. Mg + ZnSO₄ → MgSO₄ + Zn
In simple words: Only Mg lies above Zn in the list.

Teacher's Note:
1. Lead, copper and silver are below zinc.
2. Zn > Pb > Cu > Ag.

Question 16. Name two metals which can displace hydrogen from dilute HCl.
Answer:
Zinc and iron (also magnesium, aluminium).
In simple words: Metals above hydrogen displace it from acids.

Teacher's Note:
1. Zn + 2HCl → ZnCl₂ + H₂.
2. Copper does not.

Question 17. How is the corrosion of iron prevented by coating it with a layer of oil?
Answer:
The oil layer keeps oxygen and moisture away from the iron surface, so iron does not rust.
In simple words: Oil blocks air and water.

Teacher's Note:
1. Rusting needs both air and water.
2. Grease and paint also work.