CBSE Class 10 Science Chapter-3 Metals and Non-metals Important Questions – Free PDF Download
Free PDF download of Important Questions with Answers for CBSE Class 10 Science Chapter 3 – Metals and Non-metals prepared by expert Science teachers from latest edition of CBSE(NCERT) books only by CoolGyan to score more marks in CBSE board examination.
CBSE Class 10 Science Metals and Non-metals Chapter-3 Important Questions
CBSE Class 10 science Important Questions Chapter 3 – Metals and Non-metals
2 Mark Questions
1. Which Gas is produced when a metal reacts with dilute hydrochloric acid? Write the chemical reaction when iron reacts with dilute 
Ans. Hydrogen gas 
is produced when a metal reacts with dilute hydrochloric acid. Iron and dilute 
react as follows:
Hydrogen gas is evolved in this reaction also.
2. What would you observe when Zinc is added to a solution of Iron (II) sulphate? Write chemical reaction that taken place.
Ans. The green colour of solution will slowly disappear. Zinc will gradually dissolve and iron will get precipitated at the bottom of the beaker.
3. Why do ionic compounds have high melting points?
Ans. In the formations of ionic compounds, positive ions (cations) and negative ions (anions) participate. These are cloudy packed and the ionic compounds exist as crystalline solids. They have strong inter-ionic process of attraction and have high melting and forces of attraction and have high melting and boiling points.
4. Why sodium is kept immersed in kerosene oil?
Ans. Sodium reacts both with air and water. It is therefore kept in kerosene oil in order to avoid contact with both air and water.
5. State two ways to prevent the rusting of iron.
Ans. (i) By applying a coating of grease or paint
(ii) By depositing a layer of Zinc on the surface of iron.
6. What type of oxide ore is formed when nonmetals combine with oxygen?
Ans. The oxides so formed are acidic is nature which when dissolved is water, their solutions change blue litmus red for ex-
7. What are amphoteric oxides? Give examples?
Ans. Amphoteric oxides are the oxides which can act both as acids and bases for eg
Aluminium oxide 
and Zinc oxide 
8. Name two metals which can displace hydrogen from dilute acids and two metals which cannot do so?
Ans. Sodium calcium can displace hydrogen from dilute acids.
Copper and silver cannot displace hydrogen from dilute acid.
9. Give reason why platinum, gold and silver are used to make jewellary.
Ans. Platinum, Gold and silver are placed at the bottom of the activity series and are very little reactive in nature and are known as noble metals. They are not even affected by air, water and even by chemicals. Since they have bright lusture, we can use them for making jewellary.
10. Why copper is used to make hot water tanks and not steel?
Ans. Since copper is used to make hot water tanks because it is good conductor of heat than steel.
11. Can all minerals of a metal act as ores? Justify.
Ans. No, all minerals of a metal cannot act as ores but only those minerals can act as ores from which a metal can be conveniently and profitably extracted.
12. How does Galvanisation check rusting of iron?
Ans. Galvanisation means coating the surface of iron metal with zinc. Since in activity series zinc lies abore iron so it sacrifices itself for the sake of iron and prevents iron from rusting.
13. Metals are arranged in the reactivity series. Why hydrogen is kept in the series though it is not a metal?
Ans. Hydrogen is a non metal but still it is placed in the reactivity series because it behaves as an electropositive elements like metals i.e can loose electrons to form positive ions. 
14. Why are metals generally lustrous?
Ans. Metals are generally lustrous because they have a shining surface and when light falls on the surface of metal electrons absorbs photons of light and releases energy as light.
15. Corrosion of metals is not always harmful. Illustrate.
Ans. Corrosion is a very harmful process resulting in slow eating up of a metal but corrosion of aluminium is useful as a layer of aluminium oxide 
formed as result of chemical reaction and gets deposited on the surface of metal. It forms a protective coating on the surface and prevents the attacks of water, air, acids or alkalis.
16. Why does copper not liberate hydrogen on reacting with dilute sulphuric acid?
Ans. Copper is placed below hydrogen in the activity series. It cannot loose electrons to H+ ions of the acid.
Therefore, hydrogen gas is not evolved when copper reacts with dilute acid
.
17. Why does copper not liberate hydrogen on reaching with dilute sulphuric acid?
Ans. Copper is placed below hydrogen in the activity series. It can not lose electrons to H+ ions of the acid. Therefore, hydrogen gas is not evolved when copper react reacts with dilute sulphuric acid.
18. Why are non-metals gaseous at room temperature?
Ans. In the molecular from, non-metals exit as single molecules e.g. hydrogen
, Oxygen
, nitrogen
, Carbon dioxide 
and ammonia 
etc. the attractive forces in these molecules are quite weak. Therefore, they exist as gases at room temperature.
19. Both calcium and magnesium are heavier than water but still float over it. Explain.
Ans. The densities of metal Calcium and Magnesium are 1.74g/cc and 1.55g/cc respectively while that of water is 1.0g/cc at room temperature. However, both of them float over water surface. Actually hydrogen gas is evolved when these metals reacts with water. It is in the form of bubbles which stick on metal surface. Therefore, they float over water.
20. What is thermit reaction?
Ans. Thermit reaction is the reduction of certain metal oxides such as 
etc. by aluminium metal upon strong heating. It is highly exothermic in nature. For example
21. Why is sodium kept immersed in kerosene oil?
Ans. Sodium reacts so vigorously with oxygen that it catches fire when kept in the opens. Hence, to protect accidental fires, it is kept immersed in kerosene oil.
22. Write equation for the reaction of
(i) Iron with steam
(ii) Calcium and potassium with water
Ans. (i) 
(ii) 
23. Which gas is produced when dilute hydrochloric acid is added to reactive metal?
Ans. Hydrogen gas is produced when dilute hydrochloric acid is added to a reactive metal.
24. What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.
Ans. As zinc is more reactive than iron, displacement reaction will take place
25. Why do ionic compounds have high melting points?
Ans. There are strong forces of attraction between oppositely charged ions in ionic compounds. Considerable amount of energy is required to break strong inter-ionic force of attraction. Therefore, they have high melting points.
26. Which metals do not corrode easily?
Ans. Metals which are placed at the bottom of activity series like silver, gold, platinum do not corrode easily.
27. What are alloys?
Ans. An alloy is homogenous mixture of two or more metals or metal and non-metal. It is obtained by first melting primary metal and then dissolving the other element in it in definite proportion.
28. What are amphoteric oxides? Give two examples of amphoteric oxides.
Ans. Metal oxides which show both acidic as well as basic behavior are called amphoteric oxides. Such metal oxides react with both acids and bases.
Example: Aluminum oxide, zinc oxide
29. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Ans. Magnesium and zinc metals displace hydrogen from dilute acids. Copper and silver do not displace hydrogen from dilute acids.
30. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Ans. Impure metal M is made the anode, thin strips of pure metal M as cathode and a salt solution of metal M as electrolyte.
31. State two ways to prevent the rusting of iron.
Ans. Rusting of iron can be prevented by
(i) By applying grease or paint.
(ii) By galvanizing
32. A metal acts as a good reducing agent. It reduces Fe and Mn0 The reaction with Fe is used for welding broken railway tracks. Identify & the metal and write all the chemical reactions.
Ans. Aluminum
33. A yellow colored powder ‘X’ is soluble in carbon disulfide. It burns with a blue flame fanning suffocating smelling gas which turns moist blue litmus red. Identify ‘X’ and gives chemical reaction. Identify & it i metal or nonmetal.
Ans. ‘X’ is sulphur
s+0 S0
It is non metal.
34. A student set up an electric circuit as shown in Fig. He placed the metal to be tested in the circuit between terminals A and B as shown.
(i) Does the bulb glow? What does this indicate?
(ii) Why are electric wires coated with rubber like materials?
Ans. (i) Yes the bulb glows, this indicates that metal is a good conductor of electricity
(ii) Rubber like substance is a bad conductor of electricity
35. A, B and C are 3 elements which undergo chemical reactions according to following equations:
a) 
b) 
c) 
Answer of the following:
i) Which element is most reactive?
ii) Which element is least reactive?
Ans. (i) Most reactive element is B as it has replaced both A and C from their compounds.
(ii) Element C is least reactive as it has been replaced both by A and B.
36. An element X on reacting with 02 forms X Oxide dissolves in water and turns blue litmus paper red. Predict the nature of element whether it is a metal or a non metal.
Ans. The oxide is acidic in nature as it has turned blue litmus to red. Hence X is a non metal.
37. An element E combines with 02 to form an oxide E which is a good conductor of electricity. Answer the following:
(i) How many electrons will be present in the outer most shell of E?
(ii) Write the formula of the compound formed when it combines with Chlorine.
Ans. (i) Valency of the element B is l. This means that it has only one electron in the valence shell.
(ii)
Valency of Cl is 1 and Valency of B is also l. Therefore, the formula will be E.