Important Questions Class 10 Science Chapter 3 - Metals and Non-metals 3 Marks Questions

CBSE Class 10 Science Chapter-3 Metals and Non-metals Important Questions – Free PDF Download

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CBSE Class 10 Science Metals and Non-metals Chapter-3 Important Questions

CBSE Class 10 science Important Questions Chapter 3 – Metals and Non-metals

3 Mark Questions

1. Arrange the following metals in decreasing order of their reactivity:
(1) 
(2) You are provided with three metals: sodium, magnesium and copper, Using only water as the reactant, how will you identify each of them
(3) Which metal listed in (1) is most likely to occur in the native state?
Ans. (1) Based on the activity series, the decree sing order of reactivity of metals is:

(2) (a) The metal which reacts violently with cold water and catches fire is sodium
(b) The metal which evolves hydrogen gas upon heating with water is magnesium
(c) The metal which does not react with water even on strong heating is copper
(3) Copper is most likely to occur in the native (or free) state to a very small event

2. Which method of concentration of an ore is preferred in the following cases and why?
(1) The ore has higher density particles mixed with a large bulk of low density impurities
(2) The ore consists of copper sulphide intermixed with clay particles Give an example of amalgam
Ans. (1) The concentration of ore can be done by gravity separation method
(2) The concentration of ore is done by froth floatation process An amalgam of mercury with silver or gold called dental alloy is used to fill cavities in the teeth

3. (a) Why is  called a amphoteric oxide? Name another amphoteric oxide
(b) What are alkali’s? Give one example of alkali
Ans. (a) Zinc oxide (ZnO) is called amphoteric oxide as it behaves bath as acidic oxide and basic oxide

(Basic oxide) (Acid) Zinc chloride

(Acidic oxide) (Base) (Sodium zincate)
Aluminum oxide is another amphoteric oxide
(b) Water soluble hydroxides of metals are known as alkalies. For example 

4. You are given a hammer a battery, a bulb, wires and switch
(a) How could you use them to distinguish between samples of metals and non metals?
(b) Assess the usefulness of these tests to distinguish between metals and non-metals
Ans. (a) With the help of the things provided try to convert metals and non metals in the form of thin rods Metals will readily form into thin rods being malleable and non metals being brittle will break Now if we construct a cell using these rods or plates the circuit which consists of metallic rod conducts whereas non metallic rod will not conduct
(b) From these tests we can say
(i) Metals are malleable whereas nonmetals are not
(ii) Metals are good conductors of electricity while non metals are not

5. Name an alloy of
(i) Aluminium used is construction of aircrafts
(ii) lead in joining metals for electric work
(iii) copper used is house hold vessels
Ans. (i) Alloy is duralumin 
(ii) Solder 
(iii) Brass 

6. White three important properties of aluminium which are responsible for its great demand in industry?
Ans. (i) It is a good conductor of electricity
(ii) It is not attacked by water
(iii) It is a powerful reducing agent

7. Which of the following metals would give hydrogen when added to dilute HCl
(1) iron
(2) copper and
(3) magnesium
Ans. Both iron (Fe) and magnesium (Mg) will evolve hydrogen on reacting with dil HCl. These are active metals and are placed above hydrogen in the activity series As copper is placed below hydrogen in the series, if will not evolve hydrogen

8. Define an alloy and an amalgam State the main constituents of the following alloys
Stainless steel, Bronze In which property, each of them is different from its main constituent
Ans. As alloy is a homogeneous mixture of two or more metals or non- metals An alloy is which mercury is one of the constituents is called amalgam.
Stainless steel- An alloy of iron, chromium, carbon and nickel It does not get rusted whereas iron is easily rusted.
Bronze- An alloy of copper and tin, It is less malleable than copper and is used for making coins, statues etc.

9. A group of a students looked at different metals and metal sulphate solutions given is a tabular form From the data, answer the following:

(a) Which metal reacted with all other sulphate solution?
(b) Which metal did not react with any other metal sulphate solution?
(c) Arrange the metals in decreasing order of reactivity
Ans. (a) Magnesium (Mg)
(b) Copper (Cu)
(c) Decreasing order of reactivity Mg>Cr>Co>Cu

10. (1) A metal that gets covered with a protective film of its oxide (Al, Cu, Ag)
(2) A metal which burns in air with golden flame (Zn, K, Na)
(3) A metal which can displace hydrogen from boiling water as well as steam (K, Zn, Fe)
Ans. (1) Aluminium (Al)
(2) Sodium (Na)
(3) Zinc (Zn)
(4) Magnesium (Mg)

11. Write one point of difference between electrolytic reduction and reduction with carbon Give one example of each
Ans. The electrolytic reduction takes places at the cathode by the gain of electrons in electrolysis At the same time carbon reduction is carried by heating a metal oxide with coke For example

(Reduction by gain of electrons)


(Coke)(Heat) (Reduction by carbon)

12. (a) Arrange the following metals in decreasing order of their reactivity Cu, Ca, Mg, Na, Zn.
(b) You are provided with three metals: sodium, magnesium and copper Using only water as the reactant how will you identify each of them?
(c) Which metal listed in (i) is most likely to occur in the native state
Ans. (a) Na>Ca>Mg>Zn>Cu
(b) (1) Metal reacts violently with cold water and catch fire is sodium
(2) Metal which evolves H₂ gas upon heating with water is magnesium
(3) Metal which does not react with water on strong heating is copper
(c) Copper is found in native state

13. Write the equation for the reaction of
(a) Iron with steam
(b) Calcium with water
(c) Potassium with water
Ans. (a) 
(b) 
(c) 

14. Define the following terms:
(a) Minerals
(b) Ores
(c) Gangue
Ans. Minerals- These are combined state of metals generally with non-metals
Ores- The minerals from which metals can be conveniently extracted are called an ore
Gangue- It represents the earthy impurities such as mud, sand and day.

15. Pratyush took sulphur powder on a spatula and heated it He collected the gas evolved by inverting a test tube over it
What will be the action of gas in
(1) Dry litmus paper?
(2) Moist litmus paper?
Write a balanced chemical equation for the reaction taking place?
Ans. (1) The gas is sulphurdioxide It will not react with litmus paper
(2) The gas will bleach moist litmus paper The balanced of chemical equation is
S + O₂  SO₂

16. Write any three differences between metals and non-metals on the basis of chemical properties?
Ans. Difference between metals and non-metals are-

17. Why is titanium metal called as strategic metal? Mention two of its properties which makes it so special
Ans. Tritanium is called strategic metal because it is used for making certain war equipments
(1) It is light in weight but stronger
(2) It is not affected by corrosion even if kept open for a very long time

18. (a) What is corrosion?
(b) How is corrosion caused
(c) Complete the reaction 
Ans. (a) The eating up of the surface of metal if kept open for a long time is called corrosion
(b) It is caused due to the eating of metals by the gasses and water vapours present in air due to the formation of certain chemical compound
For example: surface of copper acquires a green coating due to the formation of basic copper carbonate 

Component of air

Hydrated ferric oxide (rust)

19. (1) Choose metal from the reactivity series which will not react with steam
(2) Choose one metal which will safely react with dilute sulphuric acid
(3) Name the salt formed when metal chosen in (2) reacts with sulphuric acid
Ans. (1) Gold (Au)
(2) Zinc (Zn)
(3) The salt formed is and is colourless

20. A copper plate was dipped into a solution of After sometime a black layer was deposited on the copper plate State the reason for it Write the chemical equation for the reaction involved
Ans. Copper lies above silver in the activity series This means that copper in more reactive
than silver Therefore copper had replaced silver from solution

Silver got deposited on the copper plate and changed to black after sometime because silver and also same salts of silver are sensitive to light They readily become blackish on standing or on exposure to air

21. Give an example of metal which
(i) is a liquid at room temperature
(ii) can be easily cut with knife
(iii) is best conductor of heat
(iv) is poor conductor of heat
Ans. (i) Mercury
(ii) Sodium
(iii) Silver
(iv) Lead

22. Explain the meaning of malleable and ductile
Ans. A substance that can be beaten into thin sheets is said to be malleable For example iron, copper etc.
A substance that can be drawn into wires is called ductile For example gold, silver etc

23. (i) Write the electro-dot structures for sodium, oxygen, and magnesium
(ii) Show the formation of Na2O and MgO by the transfer of electrons
(iii) What are the ions present in these compounds?
Ans. (i) Electron-dot structure for sodium, oxygen and magnesium are
(ii)

(iii) Ions present in 
Ions present in 

24. Define the following terms:
(i) Minerals
(ii) Ores and
(iii) Gangue
Ans. (i) Minerals- the element or compounds which occur naturally in the earth crest are known as minerals
(ii) Ores- Minerals from which metal can be extracted profitably and easily are called ores
(iii) Gangue- Impurities such as soil and sand which are present in the minerals are called gangue

25. Metallic oxide of zinc, magnesium and copper were heated with following metals:

In which case will you find displacement reactions taking place?
Ans. Based on the activity series of metals, the displacement reactions will take place as below:

26. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice Explain why these sour substances are effective in cleaning the vessels
Ans. Copper, on keeping in air reacts with atmospheric carbon dioxide to form a green layer of copper carbonate Copper carbonate reacts with citric acid present in lemon or tartaric acid present in tamarind to form soluble copper citrate or copper tartarate The vessels are thus cleaned using water.

27. A man went door to door posing as a goldsmith He promised to bring back the glitter of the old and dull ornaments An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution The bangles sparkled like new but their weight was reduced drastically The lady was upset but after a futile argument the man beat a hasty retreat Can you play the detective to find out the nature of the solution he had used?
Ans. Aqua regia, which is a mixture of 3 parts concentrated HCl and part of concentrated nitric acid dissolves gold The man put the gold bangles in this solution The outer dirty layer of gold bangles dissolved in aqua regia bring out the shining bangles.
As the outer layer of bangles dissolved in aqua regia, the weight was reduced drastically

28. Give reasons, why copper is used to make hot water tanks and not steel (an alloy of iron)
Ans. Electrical conductivity of a metal is decreased when it is alloyed with another metal or non-metal Thus, the electrical conductivity of steel is much less than that of pure That is why copper is used to make hot water tanks and not steel.

29. Differentiate between metal and non-metal on the basis of their chemical properties
Ans. Metals and non-metals can be differentiated on the basis of following chemical properties

30. An element reacts with oxygen to form an oxide which dissolves in dilute hydrochloric acid The oxide fanned also turns a solution of red litmus blue Is the element a metal or non-metal? Explain with the help of a suitable example
Ans. It is metal

31. Nikita took Zn, Al, Cu, Fe, M& Na metals & put each metal in cold water and then hot water She reacted the metal with steam
(i) Name the metal which reacts with cold water
(ii) Which of the above metals react with steam?
(iii) Name the metal which reacts with hot water
(iv)Arrange these metals in order of increasing reactivity
Ans. (i)Na
(ii)Al, Zn, Fe
(iii) Mg
(iv) Na>Mg>Al>Zn>Fe>Cu

32. A student was given Mg, Zn, Fe, and Cu metals He put each of them in dil HCI contained in different test tubes Identify which of them
(i) will not displace 112 from dli HCI
(ii) forms a pale green substance
(iii) will give 112 with 5% 11N0
(iv)will be displaced from its salt solution by all other metals
Ans. (i)Cu
(ii)Fe
(iii) Cu
(iv) Cu

33. A metal ‘X’ is found in the form of filings which bums vigorously when sprinkle on flame When these filings are treated with sulphur a black colured compound ‘Y’ is formed which is not attracted by magnet ‘X’ reacts with dil HCI to liberate hydrogen gas ‘X’ reacts with steam to form ‘Z’ along with hydrogen gas Identify ‘X’, ‘Y’, and ‘V Write the reaction involved
Ans.