Materials : Metals and Non – Metals| NCERT Solutions| Class 8

NCERT Solutions of  Chapter: Materials : Metals and Non – Metals. NCERT Solutions along with worksheets and notes for Class 8.

Exercises

(1) Which of the following can be beaten into thin sheets?

(a) Zinc  (b) Phosphorous   (c) Sulphur   (d) Oxygen

Ans- Metals can be beaten into thin sheets. In giving question, only zinc is a metal. Therefore, zinc can be beaten in to thin sheets.

 

(2)Which of the following statement is correct?

(a) All metals are ductile.

(b) All non – metals are ductile.

(c) Generally, metals are ductile.

(d) Some non – metals are ductile.

Ans-

(a) All metals are ductile.    Incorrect

(b) All non – metals are ductile.     Incorrect

(c) Generally, metals are ductile.   Correct

(d) Some non – metals are ductile.  Incorrect

 

(3) Fill in the blanks.

(a) Phosphorus is a very_______ non – metal.

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

(c) Iron is _______ reactive than copper.

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

Ans-

(a) Phosphorus is a very reactive non – metal.

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

(c) Iron is more reactive than copper.

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

 

(4) 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.   ( )

Ans-

(a) Generally, non – metals react with acids.    (F)

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

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

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

 

(5) Some properties are listed in the following table. Distinguish between metals and non – metals on the basis of these properties.

Properties Metals Non – metals
1. Appearance
2. Hardness
3. Malleability
4. Ductility
5. Heat Conduction
6. Conduction of Electricity

Ans-

Properties Metals Non – Metals
1. Appearance shine do not shine
2. Hardness hard soft
3. Malleability can be beaten into thin sheets cannot be beaten into thin sheets
4. Ductility can be drawn in to wires cannot be drawn in to wires
5. Heat Conduction Good conductor of heat Bad conductor of heat
6. Conduction of Electricity Good conductor of electricity Bad conductor of electricity

 

(6) 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.

Ans-

(a) Aluminium is impermeable and odourless. It prevents oxygen, light, moisture and bacteria to enter in to the food and save food to eat. Therefore, aluminium foil is good for food wrapping.

(b) Immersion rods for heating liquids are made up of metallic substances because metals are good conductors of heat and electricity. Therefore, metallic substance heated up quickly and water get warm quickly.

(c) Copper cannot displace zinc from its salt solution because zinc is more reactive metal than copper. Only more reactive metal can displace less reactive metal.

(d) Sodium and potassium metals are very reactive with water and oxygen and a lot of heat is generated in the reaction. Hence, Sodium is stored in the kerosene.

 

(7) Can you store lemon pickle in an aluminium utensil? Explain.

Ans- Metals react with acids and produce hydrogen gas. Lemon pickle has acidic nature. Therefore, lemon pickle cannot be stored in the aluminium utensils.

 

(8) Match the substances given in Column A with their uses given in Column B.

A B
(i) Gold (a) Thermometers
(ii) Iron (b) Electric wires
(iii)Aluminium (c) Wrapping food
(iv) Carbon (d) Jewellery
(v) Copper (e)Machinery
(vi) Mercury (f) Fuel

Ans- The given columns are correctly match and tabulated below-

A B
(i) Gold (d) Jewellery
(ii) Iron (e) Machinery
(iii) Aluminium (c)Wrapping food
(iv) Carbon (f) Fuel
(v) Copper (b) Electric wires
(vi) Mercury (a) Thermometers

 

(9) 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.

Ans-

(a) Dilute sulphuric acid do not react with copper. But, concentrated sulphuric acid comes in touch with copper plate, effervescence is observed. It happened because of release of hydrogen gas.

Cu + H2So4 → CuSo4 + H2

(b)When iron nails are placed in copper sulphate solution the blue colour is charged to light green colour. It happens because of iron is more reactive than the copper. Iron replaces copper from copper sulphate and forms iron sulphate.

CuSo4 + Fe → FeSo4 +Cu

 

(10) 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.

Ans-

(a) Saloni took a piece of burning charcoal and collected the gas evolved in a test tube. She will bring a wet blue litmus paper near the test tube. It will turn red. It shows gas is acidic in nature.

(b) C + O2 → Co2

Co2 + H2o → H2Co3 (carbonic acid)

 

(11) One day Reeta went to a jeweller’s shop with her mother. Her mother gave an old gold jewellery to te 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?
Ans- Generally gold does not react with acids but it react with aqua regia. It is a mixture of nitric acid and hydrochloric acid. When jeweller dip gold in aqua regia, outer layer dissolve in the mixture and we get new shinning layer. Some gold lost in this process.

Helping Topics

Materials : Metals and Non – Metals

Worksheet Class 8

Magnesium in Plants

Iron in Human Body

 

 

 

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