The solution he had used was Aqua regia. Aqua regia is Latin word which means ‘Royal Water’. It is the mixture of concentrated Hydrochloric acid and concentrated nitric acid in the ratio of 3:1. It is capable of dissolving metals like Gold and Platinum. Since the outer layer of the gold bangles is dissolved in aqua regia so their weight was reduced drastically.

 

Copper does not react with cold water, hot water, or steam. However, iron reacts with steam. If the hot water tanks are made of steel (an alloy of iron), then iron would react vigorously with the steam formed from hot water.

3Fe + 4H₂O → Fe₃O₄ + H₂O
That is why copper is used to make hot water tanks, and not steel.

1. Which of the following property is generally not shown by metals?
(a) Electrical conduction
(b) Sonorous in nature
(c) Dullness
(d) Ductility
Ans. (c) Dullness

2. The ability of metals to be drawn into thin wire is known as
(a) ductility
(b) malleability
(c) sonorousity
(d) conductivity
Ans. (a) Ductility

3. 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)
Ans. (d) (i) and (iv)
Explanation: Electrical conductivity and ductility have no relevance for a cooking utensil.

4. Which one of the following metals do not react with cold as well as hot water?
(a) Na
(b) Ca
(c) Mg
(d) Fe
Ans. (d) Iron (Fe)
Explanation: Sodium and calcium react vigorously with water. magnesium reacts with hot water to form magnesium oxide. Iron reacts with steam.

5. Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?
(a) FeO
(b) Fe₂O₃
(c) Fe₃O4
(d) Fe₂O₃ and Fe₃O4
Ans. (c) Fe₃O4

Explanation: Following equation shows the reaction between iron and steam: 

3Fe+ 4H2O → Fe₃O₄ + 4H₂O

6. What happens when calcium is treated with water?
(i) It does not react with water
(ii) It reacts violently with water
(iii) It reacts less violently with water
(iv) Bubbles of hydrogen gas formed stick to the surface of calcium
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (ii)
(d) (iii) and (iv)
Ans. (d) (iii) and (iv)
Explanation: Calcium reacts less violently with water. it starts floating because it sticks to hydrogen bubbles
Ca + H₂O -> Ca(OH)₂ + H₂

7. Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?
(a) H₂SO₄
(b) HCl
(c) HNO₃
(d) All of these
Ans. (c) HNO₃
Explanation: Nitric acid is a potent oxidizing agent. It reacts with hydrogen to form water. 

8. The composition of aqua-regia is
(a) Dil. HCl: Conc. HNO₃  (3:1)
(b) Conc. HCl: Dil.HNO₃  (3:1)
(c) Conc. HCl: Conc.HNO₃  (3:1)
(d) Dil. HCl: Dil. HNO₃  (3:1)

Ans. (b) Conc. HCl: Dil. HNO3 (3:1)4

9. Which of the following are not ionic compounds?
(i) KCl
(ii) HCl
(iii) CCl₄
(iv) NaCl
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iii)
Ans. (b) (ii) and (iii)
Explanation: These are covalent compounds. Both the constituents in each compound are non-metals. 

10. Which one of the following properties is not generally exhibited by ionic compounds?
(a) Solubility in water
(b) Electrical conductivity in solid state
(c) High melting and boiling points
(d) Electrical conductivity in molten state
Ans. (b) Electrical conductivity in solid state
Explanation: Free ions are required for electrical conductivity. In ionic compounds, free ions are not available in solid state. 

11. Which of the following metals exist in their native state in nature?
(i) Cu
(ii) Au
(iii) Zn
(iv) Ag
(a) (i) and (ii) (b) (ii) and (iii)
(c) (ii) and (iv) (d) (iii) and (iv)
Ans. (c) (ii) and (iv)
Explanation: Gold and silver are noble metals and are the least reactive metals. Hence, they are found in their native state in nature

12. 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) (iii) and (iv)
Ans. (d) (iii) and (iv)
Explanation: These metals are at the top of reactivity series. Hence, these are refined by electrolytic refining. 

13. Silver articles become black on prolonged exposure to air. This is due to the formation of
(a) Ag₃N
(b) Ag₂O
(c) Ag₂S
(d) Ag₂S  and Ag₃N₂
Ans. (c) Ag₂S

14. Galvanisation is a method of protecting iron from rusting by coating with a thin
layer of
(a) Gallium
(b) Aluminium
(c) Zinc
(d) Silver
Ans. (c) Zinc
Explanation: Applying a layer of zinc through electrolysis is called galvanization.

15. Stainless steel is very useful material for our life. In stainless steel, iron is mixed with
(a) Ni and Cr
(b) Cu and Cr
(c) Ni and Cu
(d) Cu and Au
Ans. (a) Ni and Cr

16. If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of 

(a) CuSO₄
(b) CuCO₃
(c) Cu(NO₃)₂ 
(d) CuO
Ans. (d) CuO
Explanation: When kept in open air, Copper reacts with oxygen to form copper oxide which appears as greenish layer. 

17. Generally, metals are solid in nature. Which one of the following metals is found in liquid state at room temperature?
(a) Na
(b) Fe
(c) Cr
(d) Hg 

Ans. (d) Hg
Explanation: Mercury is the metal which is present in liquid state at room temperature.

18. Which of the following metals are obtained by electrolysis of their chlorides in molten state?
(i) Na
(ii) Ca
(iii) Fe
(iv) Cu
(a) (i) and (iv)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (i) and (ii)
Ans. (d) (i) and (ii)
Explanation: These metals are at the top of reactivity series.
19. Generally, non-metals are not lustrous. Which of the following non-metal is
lustrous?
(a) Sulphur
(b) Oxygen
(c) Nitrogen
(d) Iodine
Ans. (d) Iodine

20. Which one of the following four metals would be displaced from the solution of its salts by other three metals?
(a) Mg
(b) Ag
(c) Zn
(d) Cu
Ans. (b) Ag
Explanation: Silver is the least reactive metal among the given metals.

21. 2 mL each of concentrated HCl, HNO₃ and a mixture of concentrated HCl and concentrated HNO₃ in the ratio of 3: 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put in each test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C respectively. The metal could be
(a) Al
(b) Au
(c) Cu
(d) Pt
Ans. (b) Au
Explanation: Mixture in test tube C is called Aqua Regia. It dissolves gold.

22. An alloy is 
(a) an element
(b) a compound
(c) a homogeneous mixture
(d) a heterogeneous mixture
Ans. (c) A homogeneous mixture
Explanation: Components of alloy retain their chemical properties; hence alloy cannot be a compound. Composition of alloy is uniform; hence it is a homogeneous mixture. 
 

23. An electrolytic cell consists of
(i) positively charged cathode
(ii) negatively charged anode
(iii) positively charged anode
(iv) negatively charged cathode
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (ii) ad (iv)
Ans. (b) (iii) and (iv)
Explanation: Negative charged particles (anions) move towards anode; which shows anode is positively charged.

24. During electrolytic refining of zinc, it gets
(a) deposited on cathode
(b) deposited on anode
(c) deposited on cathode as well as anode
(d) remains in the solution
Ans. (a) Deposited at cathode
Explanation: Zinc is positively charged and hence is deposited at negatively charged cathode.

25. 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. (b) Na
Explanation: Sodium is soft and can be cut with knife. It reacts so vigorously with water and air that it is kept in kerosene to prevent reaction.

26. Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents?
(a) Brass
(b) Bronze
(c) Amalgam
(d) Steel
Ans. (d) Steel
Explanation: Steel contains carbon; along with iron.

27. Which among the following statements is incorrect for magnesium metal?
(a) It burns in oxygen with a dazzling white flame
(b) It reacts with cold water to form magnesium oxide and evolves hydrogen gas
(c) It reacts with hot water to form magnesium hydroxide and evolves hydrogen gas
(d) It reacts with steam to form magnesium hydroxide and evolves hydrogen gas
Ans. (a) It burns in oxygen with a dazzling white flame
Explanation: Magnesium does not react with cold water, so option ‘b’ is incorrect. It reacts with hot water to form magnesium oxide, so options ‘c’ and ‘d’ are incorrect.

28. Which among the following alloys contain mercury as one of its constituents?
(a) Stainless steel
(b) Alnico
(c) Solder
(d) Zinc amalgam
Ans. (d) Zinc amalgam
Explanation: Alloys of mercury are called amalgam.

29. Reaction between X and Y, forms compound Z. X loses electron and Y gains electron. Which of the following properties is not shown by Z?
(a) Has high melting point
(b) Has low melting point
(c) Conducts electricity in molten state
(d) Occurs as solid
Ans. (b) Has low melting point
Explanation: Z is an ionic compound. Ionic compound have high melting point, they occur as solid and conduct electricity in molten state

30. The electronic configurations 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. (d) Y is a non-metal and Z is a metal
Explanation: Y has 7 electrons in its outermost shell. This means Y is electronegative element and hence is a non-metal. Z has 2 electrons in its outermost shell. This means Z is electropositive element and hence is a metal.

31. Although metals form basic oxides, which of the following metals form an amphoteric oxide?
(a) Na
(b) Ca
(c) Al
(d) Cu
Ans. (c) Al
Explanation: Oxide of aluminium shows both acidic and basic behaviour and hence is an amphoteric oxide.

32. 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. (b) Graphite

33. Electrical wires have a coating of an insulting material. The material, generally used is
(a) Sulphur
(b) Graphite
(c) PVC
(d) All can be used
Ans. (c) PVC
Explanation: Sulphur is highly brittle and hence cannot be used. Graphite is good conductor of electricity and hence it cannot be used for insulation.

34. Which of the following non-metals is a liquid?
(a) Carbon
(b) Bromine
(c) Phosphorus
(d) Sulphur
Ans. (b) Bromine

35. Which of the following can undergo a chemical reaction?
(a) MgSO₄ + Fe
(b) ZnSO₄ + Fe
(c) MgSO₄ + Pb
(d) CuSO₄ + Fe
Ans. (d) CuSO₄ + Fe
Explanation: Iron is more reactive than copper. Hence, iron displaces copper from copper sulphate solution.

36. Which one of the following figures correctly describes the process of electrolytic refining?



Ans. (b)
Explanation: Copper ions are liberated from positively charged anode and getting deposited on negatively charged cathode.

Burning matchstick should be brought near the evolved gas. If matchstick burns with a pop sound, it indicates evolution of hydrogen gas.

Reaction with NaOH:

M + NaOH → Na₂MO₂ + H₂

Reaction with HCl:

 M + HCl →MCl + H₂

 

 

(a) Which material will be used as anode and cathode for refining of silver metal by this process?
 Ans. During electrolytic refining, impure metal is used as anode and pure metal is used as cathode. So, impure silver will be used as anode and pure silver will be used as cathode.
 
 (b) Suggest a suitable electrolyte also.
 Ans. Silver sulphate solution can be a suitable electrolyte.
 
 (c) In this electrolytic cell, where do we get pure silver after passing electric current?
 Ans. Pure silver will be obtained on cathode; because metals are electropositive. 

It is easier to obtain a metal from its oxide than from its sulphides or carbonates. Hence, in the process of extraction of metal from metal sulphides and carbonates, they are first converted to metal oxides.