Chapter Review:

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• The materials which have the property of hard, malleable, ductile, sonorous and good conductor of heat and electricity. These are called metals.examples: iron, copper, aluminium, calcium, magnesium, etc.
• The property of metals by which they can be beaten into thin sheets is called malleability.
• The property of metal by which it can be drawn into wires is called ductility.
• Metals produce ringing sounds, They are said to be sonorous. 
• Some materials are soft and dull and they break down into powdery mass on tapping with hammer. They are not sonorous and are poor conductors of heat and electricity. These materials are called non-metals. Examples: sulphur, carbon, oxygen, phosphorus, etc.
• Metals like sodium and potassium are soft and can be cut with a knife.
• Mercury is the only metal which is found in liquid state at room
  temperature.
• General, metallic oxides are basic in nature and non-metals oxides are acidic in nature.
• Sodium metal is very reactive. It reacts vigorously with oxygen and
  water therefore, stored in kerosene.
• Phosphorus is a very reactive non-metal.It catches fire if exposed to air. To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water.
• Metals react with acids and produce metal salts and hydrogen gas that burns with a ‘pop’ sound.
• Metals are used in making machinery,automobiles, aeroplanes, trains, satellites, industrial gadgets, cooking utensils, water boilers, etc.
• Non-metals used in crackers,water purification process and fertilisers to enhance the growth of plants.
• More reactive metals displace less reactive metals from their compounds in aqueous solutions.

Exercise

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Q1. Which of the following can be beaten into thin sheets?

(a) Zinc       (b) Phosphorus

(c) Sulphur    (d) Oxygen

Answer: (a)  Zinc 

Q2. Which of the following statements is correct?

(a) All metals are ductile.

(b) All non-metals are ductile.

(c) Generally, metals are ductile.

(d) Some non-metals are ductile.  

Answer: (c) Generally, metals are ductile. 

Q3. Fill in the blanks :

(a) Phosphorus is very....... non-metal.

(b) Metals are.......... conductors of heat and .

(c) Iron........... is reactive than copper.

(d) Metals react with acids to produce......... gas.

Answer: (I) reactive

(II) good, electricity

(III) more

(iv) hydrogen.        

Q4. Mark ‘T’ if the statement is true and ‘F’ if it is false.

(a) Generally, non-metals react with acids. ( )

(b) Sodium is a very reactive metal. ( )

(c) Copper displaces zinc from zinc sulphate solution. ( )

(d) Coal can be drawn into wires. ( )

Answer: (a) (F), (b) (T), (c) (F), (d) (F).  

Q5. Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties.

Answer: 

Metals: 

1. They are lustrous.

2. They are hard.

3. They can be beaten into thin sheets. 

4. They can be drawn into wires.

5. They are good conductors of heat.

6. They are also good conductors of electricity. 

Non-Metals: 

1. They are dull.

2. They are soft.

3. They cannot be drawn into thin sheets.

4. They cannot  be drawn into wires.

5. They are poor conductors of heat.

6. They are also poor conductors of electricity.

Q6. Give reason for the following:

(i) Copper cannot displace zinc from its salt solution.

(ii) Aluminium foils are used to wrap foods items.

(iii) Sodium and potassium are stored in kerosene.

(iv) Immersion rods for heating liquids are made up of metallic substances.

Answer:

(i) In an aqueous solution, a metal can displace a less reactive metal from its salt. But zinc is more reactive than copper. And because of it, copper cannot displace zinc from its salt solution.

Cu(s) +ZnSO4 (aq)        No reaction

(ii) Aluminium foils are used to wrap foods items because aluminum metal is malleable and it can be beaten into foil.

(iii) Sodium and potassium are stored in kerosene because they are highly reactive elements and can easily catch fire with the contact of air.

(iv) Immersion rods for heating liquids are made up of metallic substances because metals are good conductors of heat and electricity.

Q7. Do you think it is possible to store lemon pickle in an aluminum utensil?

Answer:

No, it is not possible to store lemon pickle in an aluminum utensil because lemon pickle contains an acid which can react with aluminum (metal) liberating hydrogen gas. This may spoil the pickle.

Q8. Match the following with column A with column B

Column-A               Column-B

Q9. What happen when:

(i) Iron nails are placed in copper sulphate solution?

(ii) Dilute sulphuric acid is poured on a copper plate? Write word equations of the reaction involved.

Answer:

i) Iron being more reactive displaces copper from copper sulphate In this reaction, the blue color of copper sulphate fades and there is deposition of copper on the iron nail.

Fe + CuSO4        FeSO4 + Cu

ii) when dilute sulphuric acid is poured on a copper plate, there will be evolution of hydrogen gas along with the formation of blue color crystal of copper sulphate.

CuSO4 + H2SO4       CuSO4 + H2

 Mahima took a piece of burning charcoal and collected the gas evolved in a test tube.

a) How will she find out the nature of gas?

b) Mention the equation of the reaction taking place in this process.

Answer-

a) In a test tube containing gas, add a few drops of water. Now cover the test tube and shake well. After shaking, test the solution with blue litmus and red litmus. It will change from blue to red. Thus, the gas is acidic in nature.

b) Charcoal reacts with oxygen to form carbon dioxide gas.

Carbon dioxide reacts with water to form carbonic acid, which turns blue litmus paper red

 

Question-11

One day Reeta along with her mother went to the jeweler’s shop. Her mother gave old gold jewelry to the goldsmith to polish. Next day when they brought the jewelry back, they found that there was a slight loss in his weight. Can you suggest a reason for the loss in weight?

Answer-

In polishing, the jewleller put the gold jewellery in a mild acidic solution, which on reaction with acid goes into the solution. So, in this process certain amount of gold is lost to the acidic solution.

Text Book Exercise

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Q6. Give reasons for the following : 

(a) Aluminium foils are used to wrap food items.

(b) Immersion rods for heating liquids are made up of metallic substances.

(c) Copper cannot displace zinc from its salt solution.

(d) Sodium and potassium are stored in kerosene.

Answer: (a) It  mainntains the temperature of food item intact as it is a good conductor of heat.

(b) Metals are good conductors of electricity. That why immersion rods are made up of  metals.

(c) It is because copper is less reactive than zinc.

(d) It is because sodium and potassium reacts vigorously when come in contact with air or water.    

Q7. Can you store lemon pickle in an aluminium utensil? Explain.

Answer: Aluminium is a metals. Metals are more reactive with acids. That is why acidic foodstuffs like lemon pickie must not be stored in alminium utensils.  

Q8. In the following Table some substances are given in Column I. In Column II some uses are given. Match the items in column I with those in Column II.

Column I Column II

(i) Gold (a) Thermometers

(ii) Iron (b) Electric wire

(iii) Aluminium (c) Wrapping food

(iv) Carbon (d) Jewellery

(v) Copper (e) Machinary

(vi) Mercury (f) Fuel

Answer: (i) (d), (ii) (e), (iii) (c), (iv) (f), (v) (b), (vi) (a).  

Q9. What happens when :

(a) Dilute sulphuric acid is poured on a copper plate?

(b) Iron nails are placed in copper sulphate solution? Write word equations of the reactions involved.

Answer: (a) When sulphuric acid is poured on copper plate, copper sulphate is made and hydrog en gas is evolved as pe the following chemical equation :

 Copper plate + Sulphuric acid  → Copper plate + Hydrogen

(b) When iron nails are placed in copper sulphate solution , Cu is displaced by iron. Chemical equation is as follows :

Iron nails +  Copper sulphate solution → Iron sulphate + Cooper

Q10. Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.

(a) How will she find the nature of the gas ?

(b) Write down word equations of all the reactions taking place in this process.

Answer: (a) When charcoal is burnt in air , carbon dioxide gas is evolved. This gas when passed into the lime water turns it milky. This is the test of CO₂ gas.

(b) Carbon + Oxygen → Carbon dioxide gas.    

Q11. One day Reeta went to a jeweller’s shop with her mother. Her mother gave old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?

Answer: In polisihing , the jeweller put the gold jeweller in a mild acidic solution , whichon reaction with acid goes into the solution. So, in this process certain amount of gold is lost to the acidic solution.   

Additional Questions With Solutions

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Q1: What is malleability?

Ans: The property of metals by which they can be beaten into thin sheets is called malleability.

Q2: What is ductility?

Ans: The property of metal by which it can be drawn into wires is called ductility.

Q3: What is sonorous?

Ans: Metals produce ringing sounds, They are said to be sonorous.

Q4: Define metals.

Ans: The materials which have the property of hard, malleable, ductile, sonorous and good conductor of heat and electricity. These are called metals.

Q5: Define non-metals.

Ans: Some materials are soft and dull and they break down into powdery mass on tapping with hammer. They are not sonorous and are poor conductors of heat and electricity. These materials are called non-metals. Examples of non-metals are sulphur, carbon, oxygen, phosphorus, etc.

Q6: What is the property of metallic oxide?

Ans: Basic in nature.

Q7:What is the property of non-metallic oxide?

Ans: Acidic in nature.

Q8: Complete the following reaction.

(i) Magnesium (Mg) + Oxygen (O₂)® 2MGO.

(ii) Iron (Fe) + Oxygen (O₂)+ Water (H₂O) ® Fe₃ O₄ +2H_2.

Q9: Why is phosphorous is stored in water?

Ans: Phosphorus is a very reactive non-metal. It catches fire if exposed to air. To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water.

Q10: Which gas burns with Pop sound?

Ans: Hydrogen.

Q11: What does the ‘pop’ sound indicate?

Ans: The pop sound indicates the presence of hydrogen gas.

Q12: What is produced When Metals react with sodium hydroxide?

Ans: Metals react with sodium hydroxide to produce hydrogen gas.

Q13: Write the chemical formula of rust.

Ans: Fe₂O₃

 

Additional Questions With Solutions

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Q14: Identify following oxides are metallic or non-metallic.

(i) An oxide turns red litmus into blue.

(ii) An oxide turns blue litmus into red.

Ans: (i)  Metallic oxide.   (ii)   Non-metallic oxide.

Q15: Name the metal which reacts vigorously with water.

Ans: Sodium

Q16: Write the name of a non-metal which is a good conductor of electricity.

Ans: Graphite.

Q17: Define displacement reaction with example.

Ans: When a highly reactive metal react with a compound of it replaces the metal from compound such a reaction is called displacement reaction.

                   Example: CuSO₄ + Fe ® FeSO₄ + Cu (­)

(Here Fe is a highly reactive metal and Cu is a less reactive metal)

Q18: Write three physical properties of metals.

Ans: Three physical properties of metals.

(i) Metals are ductile.

(ii) Metals are malleable.

(iii) Metals are sonorous.

Ques: Write the name of a metal which found liquid at room temperature.

Ans: mercury.

Q19: Name the metals which can be cut with knife.

Ans: Sodium and Potassium.

Q20: What happens when:

(i) Dilute sulphuric acid is poured on a copper plate?

Ans: when sulphuric acid is poured on copper plate copper sulphate is made and hydrogen gas is evolved as per the following chemical equation.

copper plate +sulphuric acid → copper sulphate + hydrogen.

(ii) Iron nails are placed in copper sulphate solution

Ans: When iron nails are placed in copper sulphate solution Cu is displaced by iron and colour of solution changes.

(iii) Write word equations of the reactions involved.

Ans: Chemical eqution is as follows;

  Iron nails + sulphate → Iron sulphate + copper.

Q21. Give reasons for the following :

(i) Aluminium foils are used to wrap food items.

Ans: It maintains the temperature of food item intact as it is a good conductor of heat.

(ii) Immersion rods for heating liquids are made up of metallic substances.

Ans: Metals are good conductor of electricity. That is why immersion rods are made up of metals.

(iii) Copper cannot displace zinc from its salt solution.

Ans: It is because copper is less reactive than zinc.

(iv) Sodium and potassium are stored in kerosene.

Ans: It is because sodium and potassium reacts vigorously when come in contact with air or water.

Q22: Why is lemon pickle not stored in an aluminium utensil? Explain.

Ans: As lemon pickle contains acid which highly reactive to aluminium that resulting in destroyed of utensil.

Q23: Write the equation of rusting of iron.

Ans: 3Fe +2H₂O + O₂ → Fe₃O₄ + 2H₂

Q24: What is the product formed, when sulphur reacts in air (O2)?

Ans: It is sulphur dioxide (SO₂).

Q25: What is formed when sulphur dioxide is dissolved in water? Also write the eqution.

Ans: Sulphurous acid is formed.

So₂ + H₂O  → H₂SO₃ (Sulphurous acid)

Q26: What is the reactivity of non – metals with water?

Ans: Non-metals do not react with water.