Class 10 Metals and Non-metals Mock Test (CBSE)

Topics in Metals and Non-metals

• Physical properties of metals and non-metals
• Reaction of metals with air, water and acids
• Reactivity series
• Formation and properties of ionic compounds
• Extraction of metals
• Enrichment of ores
• Extracting metals low, middle and high in the activity series
• Refining of metals
• Corrosion and its prevention

Metals and Non-metals practice questions with answers

1. Q1Multiple choice·1 mark
   Which of the following properties is generally NOT shown by ionic compounds?

   1. (a)High melting and boiling points
   2. (b)Conduction of electricity in solid state
   3. (c)Solubility in water
   4. (d)Conduction of electricity in molten state
   Show answer and step marks

   1. Correct option: (b) Conduction of electricity in solid state+1

   Answer: (b)
2. Q2Multiple choice·1 mark
   Which of the following metals does NOT displace hydrogen from dilute hydrochloric acid?

   1. (a)Zinc
   2. (b)Copper
   3. (c)Iron
   4. (d)Magnesium
   Show answer and step marks

   1. Correct option: (b) Copper+1

   Answer: (b)
3. Q3Short answer·3 marks
   Sodium, iron and mercury are obtained from their compounds, but each by a different method. Sodium lies high, iron lies in the middle and mercury lies low in the reactivity series of metals. Iron is obtained from its oxide $Fe_2O_3$, and mercury from its sulphide ore $HgS$. (a) Name the method used to extract sodium from its compound. [1] (b) Name the reducing agent used to obtain iron from $Fe_2O_3$. [1] (c) Explain why mercury can be obtained from $HgS$ without any reducing agent. [1]
   Show answer and step marks

   1. (a) Electrolytic reduction, that is, electrolysis of the molten compound of sodium, since sodium is too reactive to be reduced by carbon.+1
   2. (b) Carbon in the form of coke, which reduces the oxide to iron in the blast furnace.+1
   3. (c) Mercury is low in the reactivity series, so its oxide is unstable and decomposes on heating to give the metal (after the sulphide is roasted to the oxide).+1

   Answer: (a) Electrolytic reduction (electrolysis of molten sodium compound). (b) Carbon (coke). (c) Mercury is low in the reactivity series, so its oxide decomposes on heating to give mercury.
4. Q4Short answer·3 marks
   Explain the process of electrolytic refining of copper. State the materials used as anode, cathode, and electrolyte.
   Show answer and step marks

   1. Anode: a thick block of impure copper.+0.5
   2. Cathode: a thin strip of pure copper.+0.5
   3. Electrolyte: acidified copper sulphate solution.+0.5
   4. At the anode, impure copper dissolves into the electrolyte as copper ions ($\text{Cu} \rightarrow \text{Cu}^{2+} + 2e^-$).+0.5
   5. At the cathode, an equivalent amount of pure copper from the solution is deposited ($\text{Cu}^{2+} + 2e^- \rightarrow \text{Cu}$).+0.5
   6. Insoluble impurities settle below the anode as anode mud, while soluble impurities go into the solution.+0.5

   Answer: Anode: impure copper; cathode: thin strip of pure copper; electrolyte: acidified copper sulphate solution. On passing current, copper from the anode dissolves as $\text{Cu}^{2+}$ ions, an equal amount of pure copper deposits on the cathode, and insoluble impurities collect below the anode as anode mud.
5. Q5Long answer·5 marks
   Zinc blende ($ZnS$), a sulphide ore of zinc, is mined along with large amounts of silica and clay, which together are called gangue. Explain how this ore is concentrated before it is roasted, describing the steps in the order they are carried out. Your answer should include: (a) the substances added to the water and the role of each, (b) how the ore particles and the gangue particles behave differently in the mixture, (c) how the concentrated ore is collected from the tank, (d) why this method is particularly suitable for sulphide ores.
   Show answer and step marks

   1. The ore is crushed to a fine powder and mixed with water to form a slurry, which is the first step of the concentration process.+1
   2. Pine oil (frothing agent) and a collector are added to the slurry; the collector makes the ore particles water-repellent so that they are wetted by oil, not water.+1
   3. Air is blown through the slurry, so the oil-coated ore particles attach to the air bubbles and rise to the surface, while the gangue particles, wetted by water, remain in the tank and settle at the bottom.+1
   4. The froth containing the ore particles is skimmed off from the surface and collected, giving a concentrated ore that is then taken for roasting.+1
   5. Sulphide ores are preferentially wetted by oil, whereas the gangue (silica and clay) is wetted by water, so the separation by froth flotation works well for sulphide ores.+1

   Answer: The crushed ore is mixed with water, pine oil and a collector are added, and air is blown in. The oil-wetted $ZnS$ particles rise with the bubbles as froth, which is skimmed off, while the water-wetted gangue settles. This froth flotation method suits sulphide ores because they are preferentially wetted by oil.

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