100 MCQs on Class 10 Science Chapter 3: Metals and Non-Metals | Important for SEBA / CBSE
In this article, you will get 100 MCQs with answers on Class 10 Science Chapter 3: Metals and Non-Metals. It includes
- SEBA 10 Years PYQ MCQs on Metals and Non-Metals.
- Different district pre-test MCQs on Metals and Non-Metals.
Related Learning Guides:
Notes on Class 10 Science Chapter 3: Metals and Non-Metals
NCERT Solutions on Class 10 Science Chapter 3: Metals and Non-Metals
1. Which of the following metals reacts violently with cold water? [HSLC 2016]
(A) Al
(B) Fe
(C) Na
(D) Ca
2. Which of the following metals reacts vigorously with oxygen? [HSLC 2017]
(A) Na
(B) Fe
(C) Cu
(D) Ag
3. Which of the following methods is suitable for preventing an iron frying pan from rusting? [HSLC 2020]
(i) Applying grease
(ii) Applying paint
(iii) Applying a coating of zinc
(iv) All of the above
4. Which of the following is not an example of metalloid? [HSLC 2023]
(A) Si
(B) Ge
(C) B
(D) Al
5. Which of the following metals is the most malleable? [HSLC 2024]
(A) Sodium
(B) Iron
(C) Gold
(D) Copper
6. If metal A displaces metal B from its solution, then [HSLC 2024]
(A) A is more reactive than B metal
(B) B is more reactive than A metal
(C) A and B metals are non-reactive
(D) A and B metals are equally reactive
7. Cinnabar is a sulphide ore of which metal? [HSLC 2024]
(A) Copper
(B) Mercury
(C) Aluminium
(D) Iron
8. Food cans are coated with tin and not with zinc because [HSLC 2018, 21, 25]
(A) zinc is more reactive than tin
(B) zinc is less reactive than tin
(C) zinc is costlier than tin
(D) zinc has a higher melting point than tin
9. 24 carat pure gold is very soft. Therefore, it is not suitable for making jewellery. To make it harder (22 carat gold), it is alloyed with 2 parts of [HSLC 2025]
(A) silver or copper
(B) copper or tin
(C) silver or zinc
(D) copper or aluminium
10. Non-metals do not displace hydrogen from dilute acids. They react with hydrogen to form [HSLC 2025]
(A) oxides
(B) hydrides
(C) carbonates
(D) water
11. Match Column-A with Column-B and choose the correct option: [HSLC 2026]
| Column-A | Column-B | |
| (i) Liquid metal at room temperature | (p) | Iodine |
| (ii) Non-metal with metallic lustre | (q) | Gold |
| (iii) Most malleable metal | (r) | Mercury |
(A) (i)→(r), (ii)→(q), (iii)→(p)
(B) (i)→(r), (ii)→(p), (iii)→(q)
(C) (i)→(p), (ii)→(q), (iii)→(r)
(D) (i)→(q), (ii)→(r), (iii)→(p)
12. When manganese dioxide is heated with aluminium powder, the following reaction takes place:
3MnO₂(s) + 4Al(s) → 3Mn(l) + X(s) + Heat.
What could be the compound ‘X’? [HSLC 2026]
(A) 2Al₂O₃
(B) 2Fe₂O₃
(C) 2AlCl
(D) 2MnO
13. ‘Te’ (Tellurium) is:
(A) A metal
(B) A non-metal
(C) A metalloid
(D) None of the above
14. ‘K’ (Potassium) is a metal. It is:
(A) Very reactive
(B) Less reactive
(C) Both (A) and (B) are correct
(D) None of the above
15. The process of applying a thick coating of aluminum oxide is:
(A) Anodizing
(B) Galvanization
(C) Oil coating
(D) Grease coating
16. An element reacts with oxygen to form a compound with high melting point. The compound is soluble in water. The possible element is:
(A) Ca
(B) C
(C) Si
(D) Fe
17. While extracting metals from sulphide ore, the ore is converted into metal oxides. This process is known as:
(A) Calcination
(B) Refining
(C) Reduction
(D) Roasting
18. Which of the following is the correct descending order of reactivity of metals?
(A) K > Ag > Zn > Cu
(B) Zn > K > Ag > Cu
(C) Zn > Cu > K > Ag
(D) K > Zn > Cu > Ag
19. Which of the following is the correct sequence according to reactivity of metal:
(A) Fe > Pb > Cu > Hg
(B) Pb > Cu > Hg > Fe
(C) Cu > Hg > Fe > Pb
(D) Hg > Fe > Pb > Cu
20. Which of the following non-metallic element is in liquid form?
(A) Carbon
(B) Hydrogen
(C) Bromine
(D) Phosphorus
21. The two products of the reaction are: Al₂O₃ + NaOH →
(A) Sodium Aluminate, H₂O
(B) Sodium Aluminate, Oxygen
(C) Sodium Ethanoate, H₂O
(D) Sodium Ethanoate, Hydrogen
Answer:- (A) Sodium Aluminate, H₂O
22. Which of the following metals do not displace H₂ gas from dilute HCl or dilute H₂SO₄?
(A) Mg
(B) Cu
(C) Zn
(D) Al
Answer:- (B) Cu
23. Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same:
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
(A) (i) and (ii)
(B) (i) and (iii)
(C) (ii) and (iii)
(D) (i) and (iv)
Answer:- (D) (i) and (iv)
24. The chemical reaction between a piece of copper and nitric acid is given by the chemical equations.
Cu + HNO₃ → Cu(NO₃)₂ + H₂ and
H₂ + HNO₃ → H₂O + NO₂.
What can be inferred from the chemical equation?
(A) Copper causes the oxidation of HNO₃ to form NO₂
(B) Hydrogen gas gets oxidised by HNO₃ to form water
(C) Hydrogen Gas reacts with oxygen in air to form water
(D) Nitrate react with hydrogen to form NO₂ and H₂O
Answer:- (B) Hydrogen gas gets oxidised by HNO₃ to form water
25. Assertion (A): Iron is the most widely used metal but it is never used in its pure state.
Reason (R): Pure iron is very soft and stretches easily when hot.
(A) Both A and R are true and R is the correct explanation of A
(B) Both A and R are true and R is not the correct explanation of A
(C) A is true but R is false
(D) A is false but R is true
Answer:- (A) Both A and R are true and R is the correct explanation of A
26. The decreasing order of rate of reaction of Fe, Al, Zn and Mg with dilute acids is –
(A) Al > Fe > Zn > Mg
(B) Zn > Al > Mg > Fe
(C) Fe > Al > Zn > Mg
(D) Mg > Al > Zn > Fe
View Answer...Answer:- (D) Mg > Al > Zn > Fe
27. Which of the following methods is not used for the prevention of corrosion?
(A) Painting
(B) Greasing
(C) Galvanising
(D) Heating
Answer:- (D) Heating
28. Which of the following oxides is amphoteric in nature?
(A) Na₂O
(B) K₂O
(C) Al₂O₃
(D) CuO
Answer:- (C) Al₂O₃
29. Which is the correct order of decreasing reactivity of metal?
(A) Mg > Fe > Al > Zn
(B) Mg > Al > Zn > Fe
(C) Zn > Fe > Mg > Al
(D) Zn > Al > Fe > Mg
Answer:- (B) Mg > Al > Zn > Fe
30. Which of the following metal is not soft?
(A) Lithium
(B) Sodium
(C) Ferrum
(D) Potassium
Answer:- (C) Ferrum
31. Which of the following compound does not conduct electricity?
(A) Na₂O
(B) H₂O
(C) MgO
(D) CaO
Answer:- (B) H₂O
32. The correct arrangement of the given metals (Zn, Fe, Mg, Na) in order of their reactivity is:
(A) Na > Fe > Mg > Zn
(B) Na > Mg > Fe > Zn
(C) Na > Zn > Mg > Fe
(D) Na > Mg > Zn > Fe
Answer:- (D) Na > Mg > Zn > Fe
33. On addition of which metal copper sulphate solution (blue in colour) will become colourless:
(A) Fe
(B) Ag
(C) Zn
(D) Hg
Answer:- (C) Zn
34. How many Carat’s of Gold is used in India to make jewellery:
(A) 20 Carat’s
(B) 24 Carat’s
(C) 22 Carat’s
(D) 16 Carat’s
Answer:- (C) 22 Carat’s
35. The process by which the impurities such as soil, sand etc. are removed from an ore mined from the earth is known as –
(A) Calcination
(B) Refining
(C) Enrichment of ore
(D) Reduction
View Answer...Answer:- (C) Enrichment of ore
36. Which one of the following is metalloid:
(A) Mg
(B) C
(C) P
(D) Ge
Answer:- (D) Ge
37. Which of the following metals can replace copper from a solution of copper sulphate?
(A) Silver
(B) Gold
(C) Zinc
(D) Mercury
Answer:- (C) Zinc
38. Lustrous non-metal is:
(A) Sulphur
(B) Oxygen
(C) Nitrogen
(D) Iodine
Answer:- (D) Iodine
39. Which of the following elements is a metalloid?
(A) Na
(B) Al
(C) Cl
(D) B
Answer:- (D) B
40. In the formation of an ionic compound K₂O, each atom of K gives how many electron(s) to an atom of O?
(A) 1
(B) 2
(C) 3
(D) 4
Answer:- (A) 1
41. ZnO and Al₂O₃ react with both acids as well as bases to produce salts and water. These metal oxides are:
(A) Basic
(B) Acidic
(C) Amphoteric
(D) Neutral
Answer:- (C) Amphoteric
42. Find out the metal which is liquid at normal temperature.
(A) Magnesium
(B) Copper
(C) Mercury
(D) Iron
Answer:- (C) Mercury
43. Ionic compounds dissolve readily in which liquid?
(A) Water
(B) Kerosene
(C) Petrol
(D) Benzene
Answer:- (A) Water
44. Utensils used in cooking are made of metals because:
(A) Metals are hard
(B) Metals are malleable
(C) Metals are tough (impact resistant)
(D) Metals are good conductors of heat and have high melting points
View Answer...Answer:- (D) Metals are good conductors of heat and have high melting points
45. Aluminium oxide is a metallic oxide. Its nature is:
(A) Acidic
(B) Basic
(C) Neutral
(D) Amphoteric
View Answer...Answer:- (D) Amphoteric
46. Roasting is carried out:
(i) In presence of excess air
(ii) In presence of limited air
(iii) In case of sulphide ores
(iv) In case of carbonate ores
(A) (i), (iii)
(B) (ii), (iv)
(C) (i), (iv)
(D) (ii), (iii)
View Answer...Answer:- (A) (i), (iii)
47. For ionic compounds which statement is correct?
(A) They conduct electricity in solid state
(B) They conduct electricity in aqueous/molten state
(C) They have low melting and boiling points
(D) They dissolve in kerosene, petrol etc.
View Answer...Answer:- (B) They conduct electricity in aqueous/molten state
48. On the basis of the reactions
Fe + CuSO₄ → FeSO₄ + Cu;
Zn + CuSO₄ → ZnSO₄ + Cu;
Pb + CuCl₂ → PbCl₂ + Cu;
Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag.
The correct descending order of metal reactivity is:
(A) Ag > Cu > Pb > Fe > Zn
(B) Pb > Ag > Cu > Zn > Fe
(C) Zn > Fe > Pb > Cu > Ag
(D) Ag > Cu
View Answer...Answer:- (C) Zn > Fe > Pb > Cu > Ag
49. Metals that react with cold or hot water are:
(A) Al and Zn
(B) Al and Mg
(C) Zn and Cu
(D) Ag and Au
View Answer...Answer:- (B) Al and Mg
50. Which of the following metals float when they react with water? (Na, Mg, Ca, Mn)
(A) Mn and Na
(B) Na and Ca
(C) Mg and Na
(D) Mg and Ca
View Answer...Answer:- (D) Mg and Ca
51. Correct order of reactivity of metals Ca, Fe, Mg, Pb is –
(A) Pb > Fe > Mg > Ca
(B) Ca > Mg > Fe > Pb
(C) Ca > Pb > Mg > Fe
(D) Ca > Mg > Pb > Fe
View Answer...Answer:- (B) Ca > Mg > Fe > Pb
52. Match Column I with Column II:
| Column I | Column II |
| 1) Soft metal | A. Bromine |
| 2) Liquid non-metal | B. Iodine |
| 3) Hard non-metal | C. Sodium |
| 4) Non-metal with metallic lustre | D. Diamond |
(A) 1→D, 2→C, 3→A, 4→B
(B) 1→C, 2→A, 3→B, 4→D
(C) 1→C, 2→A, 3→D, 4→B
(D) 1→B, 2→D, 3→A, 4→C
View Answer...Answer:- (C) 1→C, 2→A, 3→D, 4→B
53. Which metal oxide is amphoteric?
(A) MgO
(B) Na₂O
(C) ZnO
(D) K₂O
View Answer...Answer:- (C) ZnO
54. Metals extracted by electrolysis of molten chlorides or oxides are –
(A) Na
(B) Zn
(C) Hg
(D) Ag
View Answer...Answer:- (A) Na
55. Which of the following is the correct decreasing order of reactivities of metals?
(i) K > Na > Ca > Al > Pb
(ii) Na > K > Ca > Al > Pb
(iii) K > Na > Al > Pb > Ca
(iv) Na > K > Ca > Pb > Al
View Answer...Answer:- (i) K > Na > Ca > Al > Pb
56. Which of the following is a metalloid?
(A) Be
(B) S
(C) Ge
(D) Ga
View Answer...Answer:- (C) Ge
57. A metal which can be easily cut with a knife –
(A) Li
(B) Fe
(C) Cu
(D) Zn
View Answer...Answer:- (A) Li
58. Choose correct sentence:
(A) All metals occur in nature in free state
(B) All metals occur in nature in compound form
(C) Metals at bottom of reactivity series are more active
(D) Metals at bottom of reactivity series are less active
View Answer...Answer:- (D) Metals at bottom of reactivity series are less active
59. Reactants of thermite reaction are –
(A) Iron(I) oxide and aluminium
(B) Iron(II) oxide and aluminium
(C) Iron(III) oxide and aluminium
(D) Aluminium oxide and iron
View Answer...Answer:- (C) Iron(III) oxide and aluminium
60. Pure iron is very soft. To make it hard, it is mixed with –
(A) 50% carbon
(B) 5% carbon
(C) 0.5% carbon
(D) 0.05% carbon
View Answer...Answer:- (D) 0.05% carbon
61. The process in which a carbonate ore is heated strongly in absence of air to convert into metal oxide is called –
(A) Reduction
(B) Calcination
(C) Roasting
(D) Refining
View Answer...Answer:- (B) Calcination
62. Samples of four metals A, B, C and D were taken and added one by one to the solutions given below. The results are shown in the table.
| Metal | Iron (II) Sulphate | Copper (II) Sulphate | Zinc Sulphate | Silver Nitrate |
|---|---|---|---|---|
| A | No reaction | Displacement | No reaction | – |
| B | Displacement | – | No reaction | – |
| C | No reaction | No reaction | No reaction | Displacement |
| D | No reaction | No reaction | No reaction | No reaction |
The metals are arranged in the order of decreasing reactivity as:
(A) A > B > C > D
(B) D > C > B > A
(C) B > C > A > D
(D) B > A > C > D
View Answer...Answer:- (D) B > A > C > D
63. Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?
(i) Au
(ii) Cu
(iii) Na
(iv) K
(A) (i) and (ii)
(B) (i) and (iii)
(C) (ii) and (iii)
(D) (ii) and (iv)
View Answer...Answer:- (A) (i) and (ii)
64. The electronic configurations of three elements X, Y and Z are: X – 2, 8; Y – 2, 8, 7; Z – 2, 8, 2. Which of the following is correct?
(A) X is a metal, Y is non-metal, Z is a metal
(B) Y is a metal
(C) Z is a non-metal
(D) Y is non-metal, Z is metal
View Answer...Answer:- (D) Y is non-metal, Z is metal
65. The colour of the solution observed after 1 hour of placing iron metal into copper sulphate solution is—
(A) Blue
(B) Dirty Green
(C) Colourless
(D) Red
View Answer...Answer:- (B) Dirty Green
66. Match Column A with Column B:
| Column A | Column B |
| P) A metal that forms amphoteric oxide | i) Ga |
| Q) Which melts when kept on our palm | ii) Au |
| R) A metal that has high density | iii) Al |
| S) A metal which cannot displace hydrogen | iv) Os |
(a) P-(ii), Q-(i), R-(iii), S-(iv)
(A) P-(ii), Q-(i), R-(iii), S-(iv)
(B) P-(iii), Q-(i), R-(iv), S-(ii)
(C) P-(iv), Q-(ii), R-(iii), S-(i)
(D) P-(iii), Q-(ii), R-(i), S-(iv)
View Answer...Answer:- (B) P-(iii), Q-(i), R-(iv), S-(ii)
67. When we burn a magnesium ribbon, it burns with a dazzling white flame and changes into a white powder. The chemical formula of the white powder is:
(A) MgCl₂
(B) MgO
(C) Mg₂O
(D) MgO₂
View Answer...Answer:- (B) MgO
68. Ruhi used her old gold earring to make a new ring by reshaping. Due to which property of metal was this possible?
(A) Ductility
(B) Metallic lustre
(C) Malleability
(D) Hardness
View Answer...Answer:- (C) Malleability
69. Which reactivity series of metals is correctly presented?
(A) Na>K>Al>Mg
(B) Na>Ca>Mg>Al
(C) Na>K>Mg>Al
(D) Ca>Na>Al>Mg
View Answer...Answer:- (B) Na>Ca>Mg>Al
70. Match the following:
| Column I (Alloy) | Column II (Composition) |
| P. Brass | (i) Pb, Sn |
| Q. Bronze | (ii) Cu, Zn |
| R. Solder | (iii) Cu, Sn |
(A) P(ii), Q(i), R(iii)
(B) P(ii), Q(iii), R(i)
(C) P(iii), Q(ii), R(i)
(D) P(iii), Q(i), R(ii)
View Answer...Answer:- (B) P(ii), Q(iii), R(i)
71. X + YSO₄ → XSO₄ + Y. The correct pair of X and Y for the above displacement reaction are—
(A) X = Fe, Y = Zn
(B) X = Pb, Y = Zn
(C) X = Zn, Y = Cu
(D) X = Cu, Y = Fe
View Answer...Answer:- (C) X = Zn, Y = Cu
72. Match Column I (Metal or Non-metal) with Column II (Speciality):
| Column I | Column II |
| A. Br₂ | (i) Highly ductile metal |
| B. I₂ | (ii) Liquid non-metal |
| C. Au | (iii) Soft metal |
| D. Na | (iv) Lustrous non-metal |
(A) A-(ii), B-(iv), C-(iii), D-(i)
(B) A-(ii), B-(iv), C-(i), D-(iii)
(C) A-(iii), B-(i), C-(iv), D-(ii)
(D) A-(iv), B-(iii), C-(i), D-(ii)
View Answer...Answer:- (B) A-(ii), B-(iv), C-(i), D-(iii)
73. Which of the below chemical equations is an example of calcination?
(A) ZnCO₃(s) →(heat)→ ZnO(s) + CO₂(g)
(B) ZnO(s) + C(s) → Zn(s) + CO(g)
(C) 2ZnS(s) + 3O₂(g) → 2ZnO(s) + 2SO₂(g)
(D) 2HgS(s) + 3O₂(g) → 2Hg(s) + 2SO₂(g)
View Answer...Answer:- (A) ZnCO₃(s) →(heat)→ ZnO(s) + CO₂(g)
74. Assertion (A): Generally 22 carat gold is used for making ornaments in India.
Reason (R): 24 carat gold or pure gold is very soft.
(A) Both A and R are true and R is the correct explanation of A
(B) Both A and R are true and R is not the correct explanation of A
(C) A is true but R is false
(D) A is false but R is true
View Answer...Answer:- (A) Both A and R are true and R is the correct explanation of A
75. Fe₂O₃ + 2Al → Al₂O₃ + 2Fe. The above reaction is an example of –
(A) Combination reaction
(B) Double displacement reaction
(C) Decomposition reaction
(D) Displacement reaction
View Answer...Answer:- (D) Displacement reaction
76. Which metal is used in thermite process?
(A) Cu
(B) Al
(C) Co
(D) Zn
View Answer...Answer:- (B) Al
77. Solder is an alloy of lead and tin. It has a:
(A) Low melting point and is used for welding electrical wires together
(B) Low melting point used for welding heavy iron machinery
(C) High melting point used for welding electrical wires
(D) High melting point used for welding heavy iron machinery
View Answer...Answer:- (A) Low melting point and is used for welding electrical wires together
78. A metal M reacts with oxygen to form metallic oxide MO. This oxide reacts with moist CO₂ of the atmosphere to form a basic metal carbonate. The metal M is:
(A) Cu
(B) Fe
(C) Zn
(D) Cr
View Answer...Answer:- (A) Cu
79. Which of the following metals exist in their native state in nature?
(i) Au
(ii) Cu
(iii) Na
(iv) K
(A) (i) and (ii)
(B) (i) and (iii)
(C) (ii) and (iv)
(D) (iii) and (iv)
View Answer...Answer:- (A) (i) and (ii)
80. The compound formed upon combustion of potassium metal in excess air is:
(A) K₂O₂
(B) KO₂
(C) K₂O
(D) KOH
View Answer...Answer:- (B) KO₂
81. While walking on the roadside Bikram observed that many iron pipes had developed cracks and rust on their surfaces… Identify the correct statement.
(A) Rusting of iron is caused by moisture
(B) Rusting of iron is caused by only water
(C) Rusting of iron is caused only by impurities
(D) Rusting of iron is caused by oil
View Answer...Answer:- (A) Rusting of iron is caused by moisture
82. Which of the following reactions will occur?
(A) MgSO₄(aq) + Cu(s) → CuSO₄(aq) + Mg(s)
(B) CuSO₄(aq) + Fe(s) → FeSO₄(aq) + Cu(s)
(C) ZnSO₄(aq) + Pb(s) → PbSO₄(aq) + Zn(s)
(D) Na₂SO₄(aq) + Al(s) → Al₂(SO₄)₃ + Na(s)
View Answer...Answer:- (B) CuSO₄(aq) + Fe(s) → FeSO₄(aq) + Cu(s)
83. The following metals react with water to form metal hydroxide and hydrogen gas. Which of the two metals float after reacting with water?
(i) Mg
(ii) 2K
(iii) 2Na
(iv) Ca
(A) (i) and (ii)
(B) (ii) and (iii)
(C) (i), (ii) and (iv)
(D) (i) and (iv)
View Answer...Answer:- (D) (i) and (iv)
84. Which of the following metals can displace Zn from its solution?
(i) Cu
(ii) Ag
(iii) Al
(iv) Ca
(A) iii, iv
(B) i, iii
(C) ii, iii
(D) i, iv
View Answer...Answer:- (A) iii, iv
85. Which of the following elements is not a metalloid?
(A) Arsenic
(B) Antimony
(C) Tellurium
(D) Aluminium
View Answer...Answer:- (D) Aluminium
86. The process in which carbonate ores are changed to metal oxides by heating strongly in limited air is called –
(A) Roasting
(B) Calcination
(C) Refining
(D) Reduction
View Answer...Answer:- (B) Calcination
87. Metal and non-metal that exist in liquid state at room temperature are
(A) Bromine and mercury
(B) Mercury and Iodine
(C) Bromine and Chlorine
(D) Mercury and Bromine
View Answer...Answer:- (D) Mercury and Bromine
88. Assertion (A): All minerals are ore.
Reason (R): Metals are extracted from ores.
(A) Both A and R are true and R is the correct explanation of A
(B) Both A and R are true and R is not the correct explanation of A
(C) A is true but R is false
(D) A is false but R is true
View Answer...Answer:- (D) A is false but R is true
89. Which of the following is correct order of reactivity-
(A) Mg > Zn > Al > Fe
(B) Mg > Al > Zn > Fe
(C) Al > Zn > Fe > Mg
(D) Zn > Mg > Fe > Al
View Answer...Answer:- (B) Mg > Al > Zn > Fe
90. Which of the following metals react only with steam and not with cold or hot water?
(A) Na, K, Ca
(B) Al, Fe, Zn
(C) Cu, Ag, Au
(D) Mg, Ca, Na
View Answer...Answer:- (B) Al, Fe, Zn
Explanation: Metals like potassium and sodium react vigorously with cold water. Magnesium reacts with hot water. Metals such as aluminium, iron, and zinc do not react with either cold or hot water; they only react with steam to form metal oxide and hydrogen gas.
91. Generally, hydrogen gas is not evolved when a metal reacts with nitric acid ($\text{HNO}_3$). However, very dilute $\text{HNO}_3$ reacts with which pair of metals to evolve hydrogen gas?
(A) Fe and Zn
(B) Mg and Mn
(C) Cu and Al
(D) Na and K
View Answer...Answer:- (B) Mg and Mn
Explanation: Nitric acid ($\text{HNO}_3$) is a strong oxidising agent. It oxidises the hydrogen gas produced to water and itself gets reduced to nitrogen oxides. But only magnesium ($\text{Mg}$) and manganese ($\text{Mn}$) react with very dilute nitric acid to evolve hydrogen gas.
92. Aqua regia is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid. What is the correct volumetric ratio of these acids?
(A) $3 : 1$ of conc. $\text{HCl}$ to conc. $\text{HNO}_3$
(B) $1 : 3$ of conc. $\text{HCl}$ to conc. $\text{HNO}_3$
(C) $3 : 1$ of conc. $\text{HNO}_3$ to conc. $\text{HCl}$
(D) $2 : 1$ of conc. $\text{HCl}$ to conc. $\text{HNO}_3$
View Answer...Answer:- (A) $3 : 1$ of conc. $\text{HCl}$ to conc. $\text{HNO}_3$
Explanation: Aqua regia (royal water) is a fuming liquid composed of 3 parts concentrated hydrochloric acid ($\text{HCl}$) and 1 part concentrated nitric acid ($\text{HNO}_3$) by volume. It can dissolve noble metals like gold and platinum, even though neither of these acids can do so alone.
93. Silver articles turn black after some time when exposed to air. This tarnishing is due to the formation of a coating of:
(A) Silver oxide ($\text{Ag}_2\text{O}$)
(B) Silver nitrate ($\text{AgNO}_3$)
(C) Silver sulphide ($\text{Ag}_2\text{S}$)
(D) Silver carbonate ($\text{Ag}_2\text{CO}_3$)
View Answer...Answer:- (C) Silver sulphide ($\text{Ag}_2\text{S}$)
Explanation: Silver articles react slowly with traces of hydrogen sulphide gas ($\text{H}_2\text{S}$) present in the air to form a black protective coating of silver sulphide ($\text{Ag}_2\text{S}$).
94. An allotrope of carbon which conducts electricity due to the presence of free electrons in its structure is:
(A) Diamond
(B) Fullerene
(C) Graphite
(D) Coal
View Answer...Answer:- (C) Graphite
95. Which of the following non-metal has a very high melting and boiling point?
(A) Sulphur
(B) Diamond
(C) Graphite
(D) Phosphorus
View Answer...Answer:- (B) Diamond
96. During the electrolytic refining of metal, insoluble impurities settle down at the bottom of the anode and are known as______
(A) Cathode slag
(B) Ore residue
(C) Anode mud
(D) Gangue cake
View Answer...Answer:- (C) Anode mud
97. An iron nail is dipped into a blue solution of copper sulphate. What changes are observed after 20 minutes?
(A) Solution turns green and reddish-brown coating forms on the nail
(B) Solution turns colourless and white coating forms on the nail
(C) Solution remains blue and no reaction takes place
(D) Solution turns yellow and gas bubbles evolve
View Answer...Answer:- (A) Solution turns green and reddish-brown coating forms on the nail
Explanation: Iron is more reactive than copper, so it displaces copper from copper sulphate:$$\text{Fe(s)} + \text{CuSO}_4\text{(aq)} \rightarrow \text{FeSO}_4\text{(aq)} + \text{Cu(s)}$$The blue colour fades to pale/dirty green due to ferrous sulphate formation, and displaced copper deposits as a reddish-brown layer on the iron nail.
98. An alloy of mercury with any other metal is specifically termed as:
(A) Solder
(B) Amalgam
(C) Steel
(D) Bronze
View Answer...Answer:- (B) Amalgam
Explanation: If one of the metals is mercury, then the alloy is known as an amalgam.
99. Galvanised iron sheets are protected from rusting even if the zinc coating is broken because:
(A) Zinc forms a neutral carbonate barrier
(B) Zinc is more reactive than iron and oxidises preferentially
(C) Zinc is less reactive than iron and prevents electron flow
(D) Zinc dissolves completely in moisture
View Answer...Answer:- (B) Zinc is more reactive than iron and oxidises preferentially
Explanation: Zinc is more reactive than iron. Even when the coating is broken, zinc corrodes preferentially, preventing the underlying iron from oxidising.
100. Solid sodium chloride ($\text{NaCl}$) does not conduct electricity, but molten or aqueous sodium chloride conducts electricity. What is the reason for this behaviour?
(A) Solid $\text{NaCl}$ contains no ions
(B) Electrostatic forces in solid $\text{NaCl}$ keep ions in fixed positions
(C) Ions decompose into neutral atoms in water
(D) Covalent bonds break only when heated
View Answer...Answer:- (B) Electrostatic forces in solid $\text{NaCl}$ keep ions in fixed positions
Explanation: Sodium and chloride ions, being oppositely charged, attract each other and are held by strong electrostatic forces of attraction to exist as sodium chloride (NaCl). In molten state or aqueous solution, these forces weaken, allowing free movement of ions to conduct electricity.
101. Which metal is extracted from its ore by heating alone?
(A) Zinc from Zinc blende ($\text{ZnS}$)
(B) Iron from Haematite ($\text{Fe}_2\text{O}_3$)
(C) Mercury from Cinnabar ($\text{HgS}$)
(D) Aluminium from Bauxite ($\text{Al}_2\text{O}_3$)
View Answer...Answer:- (C) Mercury from Cinnabar ($\text{HgS}$)
Explanation: Mercury lies low in the reactivity series. When cinnabar ($\text{HgS}$) is heated in air, it first converts into mercuric oxide ($\text{HgO}$), which on further heating decomposes directly into liquid mercury metal:
$$2\text{HgO(s)} \xrightarrow{\Delta} 2\text{Hg(l)} + \text{O}_2\text{(g)}$$
102. Which of the following metals has such a low melting point that it melts when kept in the palm of your hand?
(A) Gallium and Caesium
(B) Aluminium and Zinc
(C) Iron and Copper
(D) Magnesium and Calcium
View Answer...Answer:- (A) Gallium and Caesium