Class 10 Science Metals and Non Metals Questions and Answers
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One Marks Questions
Question 1 Which of the following metals will melt at body temperature?
Gallium, Magnesium, Caesium, Aluminium Answer
Gallium & Caesium
Question 2 What are amphoteric oxides? Give two examples of amphoteric oxides. Answer
Those oxides of metals which show both acidic as well as basic behaviour in aqueous solutions are called amphoteric oxides.
Question 3 Why do ionic compounds have high melting points? Answer
In an ionic compound there is large electrostatic force of attraction between opposite charged ions. To overcome these forces a considerable amount of energy is needed therefore ionic compounds have high melting points.
Question 4 Why are ionic compounds usually hard? Question 5 Write the chemical equation for the reaction of hot aluminium with steam. Answer
The balanced chemical equation showing the reaction of aluminium with steam is -
2Al (s) + 3H2O (g) -> Al2O3 (s) + 3H2 (g)
Question 6 Name two highly malleable metals. Answer
Gold and Silver
Question 7 Why do silver ornaments lose their shine when kept for some time? Answer
silver react with the sulphur in air and becomes silver sulphide which is black in colour so the shine is lost
Question 8 Why do we use copper and aluminium wire for transmission of electric current? Answer
They have low resistance and ductile
2 Marks Question
Name two metals which react violently with cold water. Write any observation you would make when such a metal is dropped into water. How would you identify the gas evolved, if any, during the reactions? Answer
etals at the top of the reactivity series (Sodium potassium) react readily (violently) with cold water forming hydroxides with the liberation of H2, the heat evolved is sufficient for the hydrogen to catch fire.
Na(s) + 2H2O(l) ? NaOH(aq) + H2(g) + large amount of heat energy catches fire
K(s) + 2H2O(l) ? KOH(aq) + H2(g) + large amount of heat energy
The gas evolved during these reactions burns with a popping sound which confirms that the gas is hydrogen (H2).
Why do metals not evolve hydrogen gas with nitric acid? Answer
Hydrogen gas is not evolved when a metal reacts with nitric acid because nitric acid is a strong oxidising agent.it oxidises with the hydrogen produced to forn water and the nitric acid itself gets reduced to any of nitrogen oxide(N2O,NO,NO2).
When calcium metal is added to water the gas evolved does not catch fire but the same gas evolved on adding sodium metal to water catches fire. Why is it so? Question 4
A metal that exists as a liquid at room temperature is obtained by heating sulphide in the presence of air. Identify the metal and its ore and give the reaction involved. Answer
Hg is the metal and the ore is HgS. It is called Cinnabar.
HgS + O2 ------> Hg + SO2
Why do ionic compounds conduct electricity in molten state? Question 6
A metal A, which is used in thermite process, when heated with oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCI and NaOH. Question 7
What the constituents are of solder alloy? Which property of solder makes it suitable for welding electrical wires? Question 8
Name a metal which is poor conductor of electricity and a non metal which is good conductor of electricity. Answer
Tungsten and Bismuth are metals which is poor conductor of electricity
Graphite are non-metal which is good conductor of electricity
Name two metals which are found in nature in the Free State.
Justify the statement – ‘All ores are minerals but all minerals are not ores’. Give one example which can be called both ore and mineral. Question 10
Describe briefly the method to obtain mercury from cinnabar. Write the chemical equation for the reactions involved in the process. Answer
Cinnabar is the main ore of mercury. Mercury is obtained from its ore by Roasting. when cinnabar is heated in air, it is first converted into mercuric oxide. Mercuric oxide is then reduced to mercury on further heating.
2HgS(s) +3 O2 (g) + Heat ? 2HgO(s) + 2SO2 (g)
The reaction of metal ‘X’ with Fe2O3 is highly exothermic and is used to join railway tracks. Identify the metal ‘X’. Write the chemical equation of the reaction. Question 11
Name the constituents of bronze and write its two uses. Answer
Copper with 12% time .Sometimes alluminium /nickel/zinc are also mixed
Coins & medals, Churchbell
Name a metal/non-metal:
(a) Which makes iron hard and strong?
(b) Which is alloyed with any other metal to make an amalgam?
(c) Which is used to galvanise iron articles?
(d) Whose articles when exposed to air form a black coating? Question 13)
An alloy has low melting point and is therefore used for electrical fuse. Name the alloy and write its constituents. Answer
Solder ( Tin + Lead)
Give reasons for the following:
(i) Gold and silver are used to make jewellery.
(ii) Carbonate and sulphide ores are generally converted into oxide ores prior to reduction during the process of extraction. Question 15
Differentiate between roasting and calcinations processes giving one example of each. Answer
Roasting is a process of converting sulphide ores into oxides by heating strongly in the presence of excess air.
Roasting : 2ZnS(s) + 3O2 (g) -> 2ZnO(s) + 2SO2 (g)
Calcination is a process of converting carbonate ores into oxides by heating strongly in limited air.
Calcination : ZnCO3 (s) -> ZnO(s) + CO2 (g).
A substance X which is an oxide of a metal is used intensively in the cement industry. This element is present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X and also write the chemical reactions involved. Question 17
Why sodium is kept immersed in kerosene oil? Answer
Sodium is high reactive element. If it is kept in open it can explosively react with oxygen to catch fire. Hence to prevent accidental damage sodium is immersed in kerosene oil
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