NCERT Solutions for Class 10th Science
Chapter 3. Metals and Non-metals
1. Which of the following pairs will give displacement reactions?
(a) NaCl solution and copper metal
(b) MgCl2 solution and aluminium metal
(c) FeSO4 solution and silver metal
(d) AgNO3 solution and copper metal.
2. Which of the following methods is suitable for preventing an iron frying pan from
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) All of the above.
3. An element reacts with oxygen to give a compound with a high melting point. This
compound is also soluble in water. The element is likely to be
4. Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin.
(b) zinc has a higher melting point than tin.
(c) zinc is more reactive than tin.
(d) zinc is less reactive than tin.
5. You are given a hammer, a battery, a bulb, wires and a switch.
(a) How could you use them to distinguish between samples of metals and
(b) Assess the usefulness of these tests in distinguishing between metals and
6. What are amphoteric oxides? Give two examples of amphoteric oxides.
7. Name two metals which will displace hydrogen from dilute acids, and two metals
which will not.
Ans.1(d)Agno3 solution and copper metal.
Ans.2 Applying a coating of zinc.
Ans.4 food can is coated with tin not to Zinc because Zinc is more reactive than tin.
Ans.5 (a) We can beat the samples with hammer and the sample which will be beaten into thin sheets then it will be the metal and the sample which will not malleable is Non metal.Wecan use the battery,bulb,wires and switch to set up a circuit with both samples, the sample through which electricity would conduct will be metal,and which will not Non metal.
(b)These above tests are useful for distinguishing between Metal and non metal.These tests are based on the physical properties and not on chemical properties.
Ans.6 Those oxides that act as both acidic as well as basic oxides. Such metal oxides react with both acid and base to produce salt and water are known as amphoteric oxides.
for example- Aluminium oxide, Zinc oxides etc.
Ans.7 Metals that are more reactive than hydrogen (in reactivity series ) will displace hydrogen from dilute acids such as sodium and potassium.
Metal that are less reactive than hydrogen displace hydrogen from dilute acids.Such as- copper and silver.
Ans.8 In the electrolytic refining of metal M -
1. we would take impure metal M as anode.
2. We would take strip of pure metal M as cathode.
3. We would take solution of the salt solution of metal M as electrolyte.
Ans.9 (i) There will be no effect of evolved gas on dry litmus paper.
(ii) The evolved gas will turn the moist blue litmus to red because the gas produced is sulphur dioxide, because react with moisture to form sulphurous acid.
Ans.10 Two ways to prevent the rusting of iron are -
(i)Oiling,Greasing and painting-