I have expertise in making educational and other PPTs. Email me for more PPTs at a very reasonable price that perfectly fits in your budget. Email: parmarshivam105@gmail.com CBSE Previous Years Questions and Answers, Chapter - 3, Metals and Non-metals, Science, Class 10

1. CBSE Previous Years
Important
Science, Class 10
By Shivam Parmar
(Entrepreneur)

2. Q. 1 Name one metal and non-metal which exists in liquid state at
room temperature.
Ans. – Metal – Mercury, Non-metal – bromine.
Q. 2 Name the metal which has very low melting point and can melt
with heat of your palm.
Ans. – Gallium.
Q. 3 Name a non-metal which is lustrous and a metal which is non-
lustrous.
Ans. – Non-metal (lustrous) = Iodine (I)
Metal (non-lustrous) = Sodium (Na)

3. Q. 4 Name two metals that are soft and can be cut with a knife.
Ans. – Sodium and Potassium.
Q. 5 Give an example of a metal which is the best conductor of heat.
Ans. – Silver and Copper.
Q. 6 State two physical properties of gold which are of extreme use to
jewellers.
Ans. – Malleability, ductility, lustrous.

4. Q. 7 An element X forms an oxide which turns red litmus blue. Identify
whether X is a metal or non-metal.
Ans. – Metal, because metal oxides are basic in nature.
Q. 8 Make a distinction between metals and non-metals with respect
to the nature of their oxides.
Ans. – Metallic oxides are basic, few are amphoteric.
Non-metallic oxides are acidic, few are neutral.
Q. 9 Which gas is usually liberated when an acid reacts with a metal?
Ans. - Hydrogen gas is liberated when an acid reacts with a metal.

5. Q. 10
(a) Compare the properties of a typical metal and a non-metal on the basis
of the following:
(i) Nature of the oxide formed by them.
(ii) Conductivity
(b) Name a non-metal which is lustrous and a metal which is liquid at the
room temperature.
Ans. – (a) (i) Oxides of metal are basic/amphoteric.
Oxides of non-metal are acidic/neutral.
(ii) Metals are good conductors whereas non-metals are poor
conductors.
(b) Iodine and Mercury.

6. Q. 11
(i) 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, Z.
(ii) An element, X, on reaction with oxygen forms an oxide XO2, The
oxide when dissolved in water turns blue litmus red. State whether
element X is a metal or a non-metal.
(iii) Name the metal which is alloyed with copper to make bronze.
Ans. – (i) X – Carbon, Y – Diamond, Z – Graphite
(ii) Non-metal
(iii) Tin

7. Q. 12 State reason for the following:
(i) Non-metal cannot displace hydrogen from the acids.
(ii) Hydrogen is not a metal, yet it is placed in the activity series of
metals.
(iii) Aluminium is more reactive than iron, yet its corrosion is less than
that of iron.
Ans. –
(i) Non-metals are electron acceptors, they cannot supply electrons so
as to convert H+ ion to H2 (g).
(ii) Like metals, hydrogen can lose an electron to form positive H+ ion.
(iii) Aluminium is covered with a strong protective layer of oxide which
protects the metal from further corrosion.

8. Q. 13 Write one example of each of the following:
(i) Most malleable metal and most ductile metal.
(ii) The best conductor of heat and the poorest conductor of heat.
(iii) A metal with highest melting point and a metal with lowest melting
point.
Ans. –
(i) Gold and silver are most malleable metal and most ductile metal.
(ii) Silver is the best conductor of heat and lead is the poorest conductor
of heat.
(iii) Metal with highest melting point : Tungsten, Iron.
Metal with lowest melting point : Gallium, Cesium.

9. Q. 14 Write balanced equations for the reaction of :
(i) Aluminium when heated in air. Write the name of the product.
(ii) Iron with steam. Name the product obtained.
(iii) Calcium with water. Why does calcium start floating in water?
Ans. –
(i) 4Al + 3O2 2Al2O3 , Aluminium oxide.
(ii) 3Fe + 4H2O Fe3O4 + 4H2 , Ferric oxide.
(iii) Ca + 2H2O Ca(OH)2 + H2 , because hydrogen sticks to
calcium.

10. Q. 15 Write the balanced chemical equation for the following
reasons:
(i) When copper is heated in air.
(ii) When aluminium is heated in air.
(iii) Aluminium oxide reacts with sodium hydroxide.
Ans. –
(i) 2Cu + O2 2Cuo
(ii) 4Al + 3O2 2Al2O3
(iii) Al2O3 + 2NaOH 2NaAlO2 + H2O

11. Q. 16 An element A is soft and can be cut with a knife. This is very
reactive to air and cannot be kept open in air. It reacts vigorously with
water. Identify the element from the following :
(a) Mg
(b) Na
(c) P
(d) Ca
Ans. – Correct option : (b)
Explanation : Sodium is so soft that can be cut using a knife. It reacts with
oxygen or moisture present in air readily and reacts with water
vigorously. Because of this sodium is stored in kerosene oil to prevent any
reaction or accident due to reaction.

12. Q. 17 The electronic configuration of three elements X, Y and Z are X – 2,
8; Y – 2, 8, 7 and Z – 2, 8, 2. Which of the following is correct?
(a) X is a metal
(b) Y is a metal
(c) Z is a non-metal
(d) Y is a non-metal and Z is a metal.
Ans. – Correct option : (d)
Explanation : Atomic number of X is 10, this means this is Ne (Neon) which is
an inert gas.
Atomic number of given element Y is 2 + 8 + 7 = 17. This means it is
chlorine (Cl), which is a non metal.
Atomic number of given element Z is 2 + 8 + 2 = 12. This means it is
Magnesium (Mg), which is a metal.

13. Q. 18 Although metals form basic oxides, which of the following
metals form an amphoteric oxide?
(a) Na
(b) Ca
(c) Al
(d) Cu
Ans. – Correct option : (c)
Explanation : Oxides that react with both acids as well as bases to
produce salts and water are known as amphoteric oxides. Aluminium
oxide reacts in the following manner with acids and bases :
Al2O3 + 6HCl 2AlCl3 + 3H2O
Al2O3 + 2NaOH 2NaAlO2 + H2O

14. Q. 19 Generally, non-metals are not conductors of electricity.
Which of the following is a good conductor of electricity?
(a) Diamond
(b) Graphite
(c) Sulphur
(d) Fullerene
Ans. – Correct option : (b)
Explanation : Graphite, an allotrope of carbon is the only non-
metal which conducts electricity.

15. Q. 20 Electrical wires have a coating of an insulating material. The material,
generally used is
(a) Sulphur
(b) Graphite
(c) PVC
(d) All can be used
Ans. – Correct option : (c)
Explanation : PVC is a polymer and bad conductor of electricity. It is used as
an insulating material for covering electric wires. Graphite is good
conductor of electricity, so cannot be used as insulating material. Sulphur is
a non-metal although non-conductor of electricity but brittle in nature. So,
cannot be used as insulating material.

16. Q. 21 Which of the following non-metals is a liquid?
(a) Carbon
(b) Bromine
(c) Phosphorus
(d) Sulphur
Ans. – Correct option : (b)
Explanation : Metals are generally solid while non-metals are solid,
liquid and gas. Bromine is a non-metal and exists as liquid.

17. Thank
You
I have expertise in making
educational and other PPTs.
Email me for more PPTs at a
very reasonable price that
perfectly fits in your budget.
Email:
parmarshivam105@gmail.com