METALS AND NON-METALS CLASS 10THCBSE
Question 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.
Answer. (d) AgNO3 solution and copper metal.
(a) NaCl solution and copper metal
(b) MgCl2 solution and aluminium metal
(c) FeSO4 solution and silver metal
(d) AgNO3 solution and copper metal.
Answer. (d) AgNO3 solution and copper metal.
Question 2. Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) All of the above.
Answer.(c) Applying a coating of zinc
Question 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
(a) calcium
(b) carbon
(c) silicon
(d) iron.
Answer.(a) Calcium
Question 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.
Answer.(c) zinc is more reactive than tin.
Question 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 non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.
Answer. We have learnt that Metals are lustrous, malleable, ductile and are good conductors of heat and electricity. They are solids at room temperature, except mercury which is a liquid. Non-metals have properties opposite to that of metals. They are neither malleable nor ductile. They are bad conductors of heat and electricity, except for graphite, which conducts electricity.
(a) Here to distinguish between samples of metals and non-metals using hammer first, we will hammer the given samples of metals and non-metals one by one. We know some metals can be beaten into thin sheets. This property is called malleability. For example gold and silver are the most malleable metals. The samples which, can be converted into thin sheets on hammering hence, are metal where as Non-metal are brittle and can not be beaten into thin sheets.
Secondly, to distinguish between samples of metals and non-metals using a battery, a bulb, wires and a switch we can make use of a property of metal whereby they conduct electric current. To do this, we will arrange the things given a battery, a bulb, wires and a switch and test sample, as shown in the figure below :
The given test sample is connected in searies, and when we turn on the switch, if the bulb glow, given sample is Metal if it does not glow then it is a Non-metal.
(b)The method above is pretty useful except for graphite which despite being a Non-metal is good conductor of electricity.
Question 6. What are amphoteric oxides? Give two examples of amphoteric oxides.
Answer. We know that Metals combine with oxygen to form basic oxides. In general, most of the metal oxide are basic in nature. But some metal
oxides, such as aluminium oxide, zinc oxide, etc., show both acidic as well as basic behaviour. Such metal oxides which react with both acids as
well as bases to produce salts and water are known as amphoteric oxides.
Example (i) Aluminium oxide reacts in the following manner with acids and bases –
| Al2O3 + 6HCl | → | 2AlCl3 + 3H2O |
| Al2O3 + 2NaOH | → | 2NaAlO2 + H2O |
| | (Sodium aluminate) |
Example (ii) Similiarly Zinc Oxides, Lead Oxide are amphoteric oxides which react with both acids as well as bases to produce salts and water
Question 7. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer.
(i) Two metals which will displace hydrogen from dilute acids are - Magnesium and Aluminium
(i) Two metals which will not displace hydrogen from dilute acids are - Gold and Copper
Question 8. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Answer. In this process, the impure metal is made the anode and a thin strip of pure metal is made the cathode. A solution of the metal salt is used as an electrolyte. The apparatus is set up as shown in Figure. On passing the current through the electrolyte, the pure metal from the anode dissolves into the electrolyte. An equivalent amount of pure metal from the electrolyte is deposited on the cathode. The soluble impurities go into the solution, whereas, the insoluble impurities settle down at the bottom of the anode and are known as anode mud.
Electrolytic refining of copper. The electrolyte is a solution of acidified copper sulphate. The anode is impure copper, whereas, the cathode is a strip of pure copper. On passing electric current, pure copper is deposited on the cathode.
Question 9. Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.
(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.
Answer.
(a)
(i) The gas will not have any effect on dry litmus.
(ii) The gas will turn blue litmus red in moist state.
(b) S + O2 → SO2
Question 10. State two ways to prevent the rusting of iron.
Answer. Two ways two ways to prevent the rusting of iron.
(i) Galvanization: In this method, for preventing the rusting of iron and steel, they are coated with a thin layer of a Zinc. The galvanised iron article is protected against rusting as layer of zinc isolate the iron surface with moist air hence prevent rusting or corssion due to oxidisation..
(i) Painting : In this method, for preventing the rusting of iron and steel, they are coated with a thin layer of a paint. The painted iron article is protected against rusting as layer of paint isolate the iron surface with moist air hence prevent rusting or corssion due to oxidisation. The galvanised article is protected against rusting even if the zinc coating is broken.
Question 11. What type of oxides are formed when non-metals combine with oxygen?
Answer. When non-metals combine with oxygen, they form either acidic oxide or neutral oxide
Question 12. Give reasons
(a) Platinum, gold and silver are used to make jewellery.
(b) Sodium, potassium and lithium are stored under oil.
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
Answer:
(a) Platinum, gold and silver are used to make jewellery becuase they are very less.
(b) Metals such as potassium and sodium react so vigorously that they catch fire if kept in the open.Hence, to protect them and to prevent accidental fires, they are kept immersed in kerosene oil.
(c) Aluminium does not corrode and is a very good conductor of heat.
(d) It is easier to obtain a metal from it oxide, as compared to its sulphides and carbonates. Therefore, prior to reduction, the metal sulphides and carbonates must be converted into metal oxides.
Question 13. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
Answer. Copper oxide reacts with acids but copper itself does not react. So the copper can be washed by acidic subtances. It removes the corroded part (copper oxide) and pure copper is left behind.
Question 14. Differentiate between metal and non-metal on the basis of their chemical properties.
Answer:
(i) Iron formation: Metals from positive ions and non-metals form negative ions.
(ii) Acidic nature: Metals form basic oxides and non-metals form acidic oxide.
(iii) Reaction with water: Metals react with water but non-metals do not.
Question 15. A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a
futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
Answer. The solution, he used was aqua regia.
Question 16. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron) is not.
Answer. Hot iron reacts with steam formed by boiling water. But, copper does not react with water.
Question 7. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer.
(i) Two metals which will displace hydrogen from dilute acids are - Magnesium and Aluminium
(i) Two metals which will not displace hydrogen from dilute acids are - Gold and Copper
Question 8. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Answer. In this process, the impure metal is made the anode and a thin strip of pure metal is made the cathode. A solution of the metal salt is used as an electrolyte. The apparatus is set up as shown in Figure. On passing the current through the electrolyte, the pure metal from the anode dissolves into the electrolyte. An equivalent amount of pure metal from the electrolyte is deposited on the cathode. The soluble impurities go into the solution, whereas, the insoluble impurities settle down at the bottom of the anode and are known as anode mud.
Electrolytic refining of copper. The electrolyte is a solution of acidified copper sulphate. The anode is impure copper, whereas, the cathode is a strip of pure copper. On passing electric current, pure copper is deposited on the cathode.
Question 9. Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.
(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.
Answer.
(a)
(i) The gas will not have any effect on dry litmus.
(ii) The gas will turn blue litmus red in moist state.
(b) S + O2 → SO2
Question 10. State two ways to prevent the rusting of iron.
Answer. Two ways two ways to prevent the rusting of iron.
(i) Galvanization: In this method, for preventing the rusting of iron and steel, they are coated with a thin layer of a Zinc. The galvanised iron article is protected against rusting as layer of zinc isolate the iron surface with moist air hence prevent rusting or corssion due to oxidisation..
(i) Painting : In this method, for preventing the rusting of iron and steel, they are coated with a thin layer of a paint. The painted iron article is protected against rusting as layer of paint isolate the iron surface with moist air hence prevent rusting or corssion due to oxidisation. The galvanised article is protected against rusting even if the zinc coating is broken.
Question 11. What type of oxides are formed when non-metals combine with oxygen?
Answer. When non-metals combine with oxygen, they form either acidic oxide or neutral oxide
Question 12. Give reasons
(a) Platinum, gold and silver are used to make jewellery.
(b) Sodium, potassium and lithium are stored under oil.
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.
Answer:
(a) Platinum, gold and silver are used to make jewellery becuase they are very less.
(b) Metals such as potassium and sodium react so vigorously that they catch fire if kept in the open.Hence, to protect them and to prevent accidental fires, they are kept immersed in kerosene oil.
(c) Aluminium does not corrode and is a very good conductor of heat.
(d) It is easier to obtain a metal from it oxide, as compared to its sulphides and carbonates. Therefore, prior to reduction, the metal sulphides and carbonates must be converted into metal oxides.
Question 13. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
Answer. Copper oxide reacts with acids but copper itself does not react. So the copper can be washed by acidic subtances. It removes the corroded part (copper oxide) and pure copper is left behind.
Question 14. Differentiate between metal and non-metal on the basis of their chemical properties.
Answer:
(i) Iron formation: Metals from positive ions and non-metals form negative ions.
(ii) Acidic nature: Metals form basic oxides and non-metals form acidic oxide.
(iii) Reaction with water: Metals react with water but non-metals do not.
Question 15. A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a
futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
Answer. The solution, he used was aqua regia.
Question 16. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron) is not.
Answer. Hot iron reacts with steam formed by boiling water. But, copper does not react with water.
Additional Questions
Question 1. What happens when iron is heated to a high temperature.
Answer. Iron does not burn on heating but glows brightly.
Question 2. What happens when copper is heated to a very high temperature.
Answer. Copper does not burn, but the hot metal is coated with a layer of black substance known as copper(II) oxide.
Question 3. Write an experiment to show that copper does not react with dilute HCI and H2So4.
Answer. The small piece of magnesium, zinc, aluminium, iron and copper. Clean their surfaces by rubbing with a sand paper. Place these metals in separate test tubes. Add about 10 mL dilute hydrochloric acid to each of these test tubes. Observe carefully the rate of formation of bubbles.
We will find that the rate of formation of bubbles was the fastest in the case of magnesium.It decreases in the order Mg > Al > Zn > Fe. In the case of copper does not react with dilute HcI and H2SOO
Question 4. Write the physical properties of metals.
Answer:
(i) All metals except mercury are solid at room temperature.
(ii) Metals possess metallic luster.
(iii) They are malleable and and ductile.
(iv) They are good conductor of heat and electricity
(v) They (except sodium) are sonorous and have high density.
(vi) They are generally hard except sodium and potassium.
(vii) Metals have high boiling and melting points except sodium and potassium
Answer. Iron does not burn on heating but glows brightly.
Question 2. What happens when copper is heated to a very high temperature.
Answer. Copper does not burn, but the hot metal is coated with a layer of black substance known as copper(II) oxide.
Question 3. Write an experiment to show that copper does not react with dilute HCI and H2So4.
Answer. The small piece of magnesium, zinc, aluminium, iron and copper. Clean their surfaces by rubbing with a sand paper. Place these metals in separate test tubes. Add about 10 mL dilute hydrochloric acid to each of these test tubes. Observe carefully the rate of formation of bubbles.
We will find that the rate of formation of bubbles was the fastest in the case of magnesium.It decreases in the order Mg > Al > Zn > Fe. In the case of copper does not react with dilute HcI and H2SOO
Question 4. Write the physical properties of metals.
Answer:
(i) All metals except mercury are solid at room temperature.
(ii) Metals possess metallic luster.
(iii) They are malleable and and ductile.
(iv) They are good conductor of heat and electricity
(v) They (except sodium) are sonorous and have high density.
(vi) They are generally hard except sodium and potassium.
(vii) Metals have high boiling and melting points except sodium and potassium
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