NCERT Exemplar Problems and their Solutions

Reviewed By:
Krishna Kant Majee
M.Sc., B.Ed.

Chapter 3-Metal and Non-metals-MCQs

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

Explanation: Metallic luster is the characteristic feature of metals that is due to presence of free electrons.

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

Explanation: Ductility can be defined as the property of metals to drawn in thin wires by application of force on them.

Q.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)

Explanation: Some of the most common properties of Aluminium are good thermal conductivity, malleability, light weight and high melting point which make it useful for making cooking utensils.

Q.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

Explanation: Na, Ca and Mg are reactive metals and quickly react with water. At room temperature, the reaction of Fe is very slow but red hot iron reacts with steam to form Fe3O4 with hydrogen gas.
$3Fe + 4H_{2}O \rightarrow Fe_{3}O_{4} + 4 H_{2}$

Q.5. Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?
(a) FeO
(b) $Fe_{2}O_{3}$
(c) $Fe_{3}O_{4}$
(d) $Fe_{2}O_{3} and Fe_{3}O_{4}$

Explanation: Prolong heating of red hot iron with steam form Fe3O4 with hydrogen gas.
$3Fe + 4H_{2}O \rightarrow Fe_{3}O_{4} + 4H_{2}$

Q.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)

Explanation: Calcium reacts less violently with water producing the bubbles of hydrogen gas along with calcium hydroxide (Ca(OH)2).
$Ca (s) + 2H_{2}O (l)\rightarrow Ca(OH)_{2} (aq) + H_{2} (g)↑$

Question. 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) $H_{2}SO_{4}$
(b) HCI
(c) $HNO_{3}$
(d) All of these

Explanation: Nitric acid $(HNO_{3})$ is a strong oxidizing agent so it does not give hydrogen gas with metals (except Mn and Mg). As hydrogen gas is formed in the reaction $HNO_{3}$ oxidizes this hydrogen to water.

Question. 8 The composition of aqua-regia is
(a) Dil.HCI : Conc. $HNO_{3} ↔ 3 : 1$
(b) Conc. HCI: Dil. $HNO_{3} ↔ 3 : 1$
(c) Conc. HCl: Conc. $HNO_{3} ↔ 3 : 1$
(d) Dil. HCl: Dil. $HNO_{3} ↔ 3 : 1$

Explanation: Aqua-regia is a mixture of concentrated HCl and concentrated HNO3 in 3 : 1 ratio.

Q.9. Which of the following are not ionic compounds?
(i) KCl
(ii) HCl
(iii) $CCl_{4}$
(iv) NaCl
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iii)

Explanation: Ionic compounds are formed by combination of cation and anions. HCl and $CCl_{4}$ are formed by equal sharing of electrons between atoms in the molecule. Here HCl is a polar covalent compound and $CCl_{4}$ is a non-polar covalent compound.

Q.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

Explanation: Ionic compounds can conduct electricity in molten or aqueous state due to presence of free ions. In solid state, no free or mobile ions are available for conducting electricity.

Q.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)

Explanation: Gold and silver (Au and Ag) are also known as Noble metals as they are less reactive and exist in their native state in nature.

Q.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) (ii) and (iv)

Explanation: Alkali metals are very reactive so cannot refine with the help of electrolytic refining process.

Q.13. Silver articles become black on prolonged exposure to air. This is due to the formation of
(a) $Ag_{3}N$
(b) $Ag_{3}O$
(c) $Ag_{2}S$
(d) $Ag_{2}S and Ag_{3}N$

Explanation: Silver metal reacts with atmospheric sulphur compounds like H2S gas and form black coating of Ag2S over surface.

Q.14. Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of
(a) Gallium
(b) Aluminium
(c) Zinc
(d) Silver

Explanation: Zinc (Zn) metal is used to protect iron surface from rusting.

Q.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

Explanation: Stainless steels are formed with the addition of high proportion of chromium and nickel to iron.

Q.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) $CuSO_{4}$
(b) $CuCO_{3}$
(c) $Cu(NO_{3})_{2}$
(d) CuO

Explanation: Copper reacts with moist carbon dioxide in the air and form green colour basic copper carbonate.

Q.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

Explanation: At room temperature, mercury is found in liquid state.

Q.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)

Explanation: Usually alkali and alkaline earth metals can be extracted by electrolysis of their salts in molten state.

Q.19. Generally non-metals are not lustrous. Which of the following non-metals is lustrous?
(a) Sulphur
(b) Oxygen
(c) Nitrogen
(d) Iodine

Explanation: Iodine is a non-metal with lustrous appearance and exists in solid state.

Q.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

Explanation: Least reactive metal can be displaced from its solution by other three metals. Silver is least reactive out of given four metals.

Q.21. 2 mL each of conc. HCl, $HNO_{3}$, and a mixture of conc. HCl. and conc. $HNO_{3}$, in the ratio of 3 : 1 were taken in test tubes labeled 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. The metal could be
(a) Al
(b) Au
(c) Cu
(d) Pt

Explanation: A mixture of conc. HCI and conc. $HNO_{3}$ in the ratio of 3: 1 forms aqua-regia which can dissolve gold (Au) and platinum (Pt).

Q.22. An alloy is
(a) An element
(b) A compound
(c) A homogeneous mixture
(d) A heterogeneous mixture

Explanation: A homogeneous mixture of different metals or a metal and a non-metal is called as alloy.

Q.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) and (iv)

Explanation: There is a positively charged anode and negatively charged cathode in an electrolytic cell.

Q.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

Explanation: During electrolytic refining the pure zinc metal is deposited on cathode.

Q.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

Explanation: Sodium is a soft, reactive alkali metal.

Q.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

Explanation:
(a) Brass- Copper and zinc
(b) Bronze- Copper and tin
(c) Amalgam- Mercury with other metals
(d) Steel- Iron with carbon

Q.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.

Explanation: Magnesium metal does not react with cold water but reacts with both hot water and steam to form magnesium hydroxide and hydrogen gas.

Q.28. Which among the following alloys contain mercury as one of its constituents?
(a) Stainless steel
(b) Alnico
(c) Solder
(d) Zinc amalgam

Explanation:
(a) Stainless steel – Fe with C
(b) Alnico – Al, Ni and Co
(c) Solder – Pb and Sn
(d) Zinc amalgam – Zn with Hg

Q.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

Explanation: Since Z is formed from X and Y by complete transfer of electrons therefore Z should be ionic compound which must have high melting point and conductivity in molten state and usually occur as solids.

Q.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

Explanation: Metals have 1 or 2 electrons in their valance shell whereas non-metals have 5-7 valence electrons. Here X has octet configuration so it should be a Noble gas.

Q.31. Although metals form basic oxides, which of the following metals form an amphoteric oxide?
(a) Na
(b) Ca
(c) Al
(d) Cu

Explanation: Some of the metals like Aluminium (Al) metal forms amphoteric oxide $(Al_{2}O_{3}) which can behave like acid as well as base. Q.32. Generally non-metals are non-conductors of electricity. Which of the following is a good conductor of electricity? (a) Diamond (b) Graphite (c) Sulphur (d) Fullerene Answer. (b) Explanation: Graphite is one of the allotropes of carbon which shows layers arrangement of carbon atoms. The fourth valence electron of each carbon is free to move that makes it good conductor of electricity. Q.33. Electrical wires have a coating of an insulating material. The material, generally used is (a) Sulphur (b) Graphite (c) PVC (d) All can be used Answer. (c) Explanation: An insulating substance is required to coat the electrical wire such as PVC. Q.34. Which of the following non-metals is a liquid? (a) Carbon (b) Bromine (c) Phosphorus (d) Sulphur Answer. (b) Explanation: Bromine is a non-metal which exists in liquid state. Q.35. Which of the following can undergo a chemical reaction? (a)$MgSO_{4}$+ Fe (b)$ZnSO_{4}$+ Fe (c)$MgSO_{4}$+ Pb (d)$CuSO_{4}\$ + Fe