Class 10 Metals and Non-Metals Previous Years Questions : Solutions

Metals and Non-Metals Previous Years Questions : Solutions

• Show the formation of Na₂O by the transfer of electrons. [CBSE 2019] [2 Marks]
  Sol:
  
• Show the formation of magnesium oxide by the transfer of electrons. [CBSE 2019] [2 Marks]
  Sol:
  
  
• What are ionic compounds ? Why do ionic compounds not conduct electricity in the solid state? [CBSE 2019] [2 Marks]
  Sol:
  The compound formed by the transfer of electrons from a metal to a non-metal is known as ionic compound. Ex:- NaCl, Na₃PO₄ etc.
  Ionic compounds do not coduct electricity in a solid state because they have not free ions. but in liquid state ions move freely so, it can conduct electricity in liquid state.
• Out of three metals P, Q and R, P is less reactive than Q and R is more reactive than P and Q both. Suggest an activity to arrange P, Q and R in order of their decreasing reactivity. [CBSE 2019] [3 Marks]
  Sol:
  Salt solution of Metal P, Q and R were taken.
  According to the question P< Q < R. Since R is more reactive than P and Q. So, the displacement reaction takes place.
  (i) R + Salt of Q → Salt of R + Q
  R + Salt of P → Salt of R + P
  (ii) Q + Salt of R → No reaction
  Q + Salt of P → Salt of Q + P
  (iii) P + Salt of Q → No reaction
  P + Salt of R → No reaction
• Name the ore of mercury. With the help of balanced chemical equations, explain the process of extraction of mercury from its ore. [CBSE 2019] [3 Marks]
  Sol:
  The Ore of mercury is Cinabar (HgS)
  Extraction of mercury (Hg) from its ore cinnabar (HgS):-
  Roasting :-
  2HgS + 3O₂ → 2HgO + 2SO₂
  Reduction:-
  2HgO → 2Hg + O₂
  HgS → Mercuric sulphide
  HgO → Mercuric oxide
  
• Two ores X and Y were taken. On heating these ores it was observed that
  i. ore X gives CO₂ gas, and
  ii. ore Y gives SO₂ gas.
  Write steps to convert these ores into metals, giving chemical equations of the reactions that take place. [CBSE 2020] [5 Marks]
  Sol:
  (i) Ore X is Metal carbonate. (XCO₃)
  (ii) Ore Y is Metal sulphide. (YS)
  Exatraction of Ore X :
  Calcination
  XCO₃ → XO + CO₂
  Reduction
  XO + C → X + CO
  Exatraction of ore Y :
  Roasting
  2YS + 3O₂ → 2YO + 2SO₂
  Reduction
  YO + C → Y + CO
• 
  i. With the help of a diagram explain the method of refining of copper by electrolysis.
  ii. How are broken railway tracks joined? Give the name of the process and the chemical equation of the reaction involved. [CBSE 2020] [5 Marks]
  Sol:
  (i) Pure copper is made anode and thin strip of impure copper is made cathode.
  A solution of acidified copper sulphate is taken as electrolyte.
  On passing the current the pure metal from the anode dissolves into the electrolyte and equivalent amount of pure metal is deposited on the cathode.
  
  (ii) Broken railway tracks joined by filling the gaps with molten iron formed in the reaction of Fe2O3 with aluminum powder.
  The reaction takes place is Thermit Reaction.
  Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + Heat
• 
  i. What is an amalgam?
  ii. Why is solder used for making electrical fuse?
  iii. What is galvanisation? State its significance.
  iv. In the electrolytic refining of copper, name the anode and cathode used and electrolyte taken in the cell. [CBSE 2020] [5Marks]
  Sol:
  (i) Amalgam is an alloy of mercury.
  (ii) Solder used for making electrical fuses because it has low melting point.
  (iii) The process of coating the metals surface with a thin layer of zinc to prevent corrosion is called galvanisation.
  (iv) Anode is Pure copper metal.
  Cathode is thin strip of impure copper metal.
  and, Electrolyte is solution of metal salt.
• .
  i. Explain the formation of ionic compound, Al₂O₃ with electron-dot structure.
  (Given atomic number of Al and O are 13 and 8 respectively)
  ii. What happens when (report only observations)
  a. a reactive metal reacts with a dilute mineral acid ?
  b. an amphoteric oxide reacts with sodium hydroxide solution ?
  c. a metal of low reactivity is dropped in the salt solution of a metal high reactivity ?
  d. a metal carbonate is treated with acid ? [CBSE 2020] [5 Marks]
  Sol:
  (i) Electron dot structure of Al₂O₃ :
  
  (ii) a). When a reactive metal reacts with a dillute mineral acid product form is salt and evolution of Hydrogen gas.
  Metal + Dilute acid → Salt + Hydrogen
  b). When an amphoetric oxide reacts with sodium hydroxide products form are sodium aluminate and water.
  Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
  NaAlO₂ is Sodium aluminate.
  c). When a metal of low reactivity is dropped in the salt solution of a metal of high reactivity, no reaction is observed because it can’t displace high reactive metal.
  d). When a metal carbonate treated with an acid products forms are salt, water and brisk effervescence is observed.
  Metal carbonate + Acid → Salt + Water + Carbon dioxide
• .
  i. Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores.
  ii. How is copper extracted from its sulphide ore ? Explain the various steps supported by chemical equations. Draw labelled diagram for the electrolytic refining of copper. [CBSE 2018] [5 Marks]
  Sol:
  (i) Steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores :
  Ex:
  Calcination
  ZnCO₃ → ZnO + CO₂
  Reduction
  ZnO + C → Zn + CO
  (ii) Extraction of copper from its ore copper sulphide (Cu₂S) :
  Roasting
  2Cu₂S + 3O₂ → 2Cu₂O + 2SO₂
  Reduction
  2Cu₂O + Cu₂S → 6Cu + SO₂.
  Electrolytic refining of copper :