CBSE Class 10 Science Metals and Non Metals Assignment Set B

Very Short Answer Type Questions

Question. A green layer is gradually formed on a copper plate left exposed to air for a week in a bathroom. What Could this green substance be?
Ansert: It is due to the formation of basic copper carbonate (CuCO₃.Cu(OH)₂.

Question. What is amphoteric oxide? Give examples.
Ansert: Those oxides which reacts with acids as well as bases to produce salts and water are called amphoteric Oxides. E.g. Na₂O, ZnO etc.

Question. Which gas is liberated when a metal reacts with an acid? How will you test the presence of this gas?
Ansert: Hydrogen gas is formed. Bring a burning matchstick near to it, H₂ will burn explosively with ‘pop’ Sound.

Question. Name the metal which reacts with a very dilute HNO₃ to evolve hydrogen gas.
Ansert: Magnesium.

Question. Name the metal which is generally stored under kerosene and easily cut with knife.
Ansert: Sodium

Question. Why does calcium float in water?
Ansert: It is because hydrogen gas formed which sticks to surface of calcium, therefore it floats.

Question. Name a non-metal which is lustrous and a metal which is non-lustrous.
Ansert: Iodine is a non-metal which is lustrous and lead is a non-lustrous metal.

Short Answer Type Questions

Question. What would you observe when zinc is added to a solution of iron (II) sulphate? Write the chemical Reaction that takes place.
Ansert: Zinc is more reactive than iron. When zinc is added to a solution of iron (II) suphate, green color Of iron (II) sulphate fades out and iron metal is deposited.
Zn(s) + FeSO₄(aq) —–→ Fe(s) + ZnSO₄(aq)

Question. Differentiate between metal and non-metal on the basis of chemical properties.
Ansert: Difference between metals and non-metals on the basis of chemical properties.

Question. What is meant by reactivity series of metals? State which of the following chemical reaction will takes Place giving suitable reason for each.
(a) Zn + CuSO₄ ——→ ZnSO₄ + Cu
(b) Fe + ZnSO₄ ——→ FeSO₄ + Zn
(c) Zn + FeSO₃ ——→ ZnSO₄ + Fe
Ansert: Reactivity series is a series of metals arranged in the order of their decreasing order of reactivity.
(a) Reaction will take place because Zn is above Cu in the reactivity series and more reactive then Cu.
(b) Reaction will not take place as Fe is below Zn in the reactivity series cannot displace Zn from its Solution.

Question. (i) Write the electron-dot structures for sodium and magnesium.
(ii) What are the ions present in Na2O and MgO.
Ansert: (i) Electron-dot structures of sodium and magnesium:

        (ii) Ion present in Na₂O is Na⁺ and O^2-
             Ion present in MgO is Mg²⁺ and O^2-

Question. Why do ionic compound have high melting points?
Ansert: Ionic compounds do not exist as single molecules but exist as aggregates of a large number of positive And negative ions due to strong electrostatic forces. Thus, large amount of energy is required to break The inter-ionic attraction, hence these have high melting points.

Question. Swasti took sulpher powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in the figure.

(a) What will be the action of gas on
(i) Dry litmus paper?
(ii) Moist litmus paper?
(b) Write a balanced chemical equation for the reaction taking place?
Ansert: (a) (i) no action on dry litmus paper (ii) moist litmus paper becomes re as the reaction taking place.
(b) Balanced equation for the reaction taking place:
         S + O₂ —-→ SO₂

Question. Using the electronic configuration, explain how magnesium atom combines with oxygen atom to form Magnesium oxide by transfer of electrons.
Ansert: Atomic no. of magnesium = 12

Long Answer Type Questions

Question. A non-metal A is the largest constituent of air, when heated with H₂ in 1:3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with O₂ it gives an oxide C. If this oxide is passed into water in the presence Of air it gives an acid D which acts as a strong oxidizing agent.
(a) Identify A, B, C and D
(b) To which group of periodic table does this non-metal belongs?
Ansert: (a) A = N₂ Nitrogen
B = NH₃Amonia
C = NO Nitrogen
D = HNO₃ Nitric oxide
(b) element A belongs to group 15 of the periodic table. Metal

Question. (a) In the formation of compound between two atoms A and B, A loses two electrons and B gains one Electron.
(i) What is the nature of bond between A and B?
(ii) Suggest the formula of the compound formed between A and B.
(b) On similar lines explain the formation of MgCl2 molecule.
(c) Common salt conducts electricity only in the molten state. Why?
(d) Why is melting point of NaCl high?
Ansert: (a)

(c) Common salt is an ionic compound which conducts electricity only in molten state because in molten state
The electrostatic forces of attraction between opposite charged ions are overcome due to heat.
Thus ions Move freely and conduct electricity.
(d) NaCl is an ionic compound so there is a strong force of attraction between the positively charged Na Ion and negatively charged chloride ion. Therefore, a considerable amount of energy is required

Question. Explain the following:
(a) Reactivity of Al decreases if it is dipped in HNO₃.
(b) Carbon cannot reduce the oxides of Na or Mg.
(c) Iron articles are galvanized.
Ansert: (a) When Al metal reacts with HNO₃, Al₂O₃ is formed which further gets deposited on aluminum metal. Hence, more Al metal is not available for the reaction because Al₂O₃ layer is passive in nature.
(b) Na and Mg both metals are very reactive. These metals have more affinity towards oxygen than carbon. Hence, carbon cannot reduce the oxides of these metals.
(c) Galvanization is a process to protect iron from rusting. Iron get rusted when come in contact with air and moisture.

Question. State reason for the following:
(i) Lemon is used for restoring the shine of tarnished copper vessels’
(ii) Copper wires are used in electrical connections.
Ansert: (i) when a copper object remains in damp air for a considerable time, the copper reacts slowly with Caron dioxide and water in air to form a green coating of basic copper carbonate on its surface. If corroded copper vessels are treated with lemon which is acidic in nature, the acid solution dissolves Green color basic copper carbonate and makes them look shiny.
(ii) Copper metal is the next best conductor of electricity after silver metal. So electric wires are made of copper.