Thursday, March 11, 2021

Metals and Non-metals | Class 10 | Activities in NCERT Text Book with Solution

Metals and Non-metals | Activities in Text Book with Solution

Activity 3.1 

Take samples of iron, copper, aluminium and magnesium. Note the appearance of each sample.
  • Answer: They have less shiny surface.
Clean the surface of each sample by rubbing them with sand paper and note their appearance again.
  • Answer: They become more shiny.
Activity 3.2 

Take small pieces of iron, copper, aluminium, and magnesium. Try to cut these metals with a sharp knife and note your observations.
  • Answer: They are very hard to cut. Hardness varies from metal to metal.
Hold a piece of sodium metal with a pair of tongs.
CAUTION: Always handle sodium metal with care. 

Dry it by pressing between the folds of a filter paper.

Put it on a watch-glass and try to cut it with a knife.

What do you observe?
  • Answer: Sodium can be cut easily.
Activity 3.3 

Take pieces of iron, zinc, lead and copper.

Place any one metal on a block of iron and strike it four or five times with a hammer. What do you observe?

Repeat with other metals.

Record the change in the shape of these metals.
  • Answer: The metals can be beaten into thin sheets (Malleability).
Activity 3.4

Consider some metals such as iron, copper, aluminium, lead, etc.

Which of the above metals are also available in the form of wires? 
  • Answer: Iron, copper and aluminium.
Activity 3.5 

Take an aluminium or copper wire. Clamp this wire on a stand, as shown in Figure.


Fix a pin to the free end of the wire using wax.

Heat the wire with a spirit lamp, candle or a burner near the place where it is clamped.

What do you observe after some time?
  • Answer: It melts wax and the pin drops. 
Note your observations. Does the metal wire melt?
  • Answer: No. The metal wire does not melt.
Activity 3.6 

Set up an electric circuit as shown in Figure.


Place the metal to be tested in the circuit between terminals A and B as shown.

Does the bulb glow? What does this indicate?
  • Answer: Yes. The bulb glows. It indicates that metals are good conductors of electricity.
Activity 3.7

Collect samples of carbon (coal or graphite), sulphur and iodine.

Carry out the Activities 3.1 to 3.6 with these non-metals and record your observations.
  • Answer: 

Element &

Symbol

Type of surface

Hardness

Malleability

Ductility

Conducts Electricity

Sonority

Graphite (C)

Non-lustrous

Hard

No

No

Yes

No

Coal (C)

Non-lustrous

Hard

No

No

No

No

Sulphur (S)

Non-lustrous

No

No

No

No

No

Iodine (I)

Lustrous

No

No

No

No

No


Activity 3.8 

Take a magnesium ribbon and some sulphur powder.

Burn the magnesium ribbon. Collect the ashes formed and dissolve them in water.

Test the resultant solution with both red and blue litmus paper.

Is the product formed on burning magnesium acidic or basic?
  • Answer: Basic. Mg(OH)2
Now burn Sulphur powder. Place a test tube over the burningsulphur to collect the fumes produced.

Add some water to the above test tube and shake.

Test this solution with blue and red litmus paper.

Is the product formed on burning Sulphur acidic or basic?
  • Answer: Acidic. Sulphurous acid (H2SO3).
Can you write equations for these reactions?
  • Answer:

2Mg(s) + O2(g) → 2MgO(s)

MgO(S) + H2O(l) → Mg(OH)2 (aq)

S(s) + O2(g) → SO2(g)

SO2(g) + H2O(l) → H2SO3 (aq)


Activity 3.9 

CAUTION: The following activity needs the teacher’s assistance. It would be better if students wear eye protection.

Hold any of the samples taken above with a pair of tongs and try burning over a flame. Repeat with the other metal samples.

Collect the product if formed.

Let the products and the metal surface cool down.

Which metals burn easily?
  • Answer: Sodium.
What flame colour did you observe when the metal burnt?
  • Answer: Yellow.
How does the metal surface appear after burning?
  • Answer: Silver white.
Arrange the metals in the decreasing order of their reactivity towards oxygen.
  • Answer: Na > Mg > Al > Zn > Fe > Pb > Cu
Are the products soluble in water?
  • Answer: Sodium oxide is soluble in water. Other metal oxides are insoluble.
Activity 3.10 

CAUTION: The following activity needs the teacher’s assistance.

Collect the samples of the same metals as in Activity 3.9.

Put small pieces of the samples separately in beakers half-filled with cold water.

Which metals reacted with cold water? Arrange them in the increasing order of their reactivity with cold water.
  • Answer: Sodium, Potassium and Calcium react with cold water. Their increasing order of reactivity with cold water is Ca < K < Na.
Did any metal produce fire on water?
  • Answer: Yes, Sodium and Potassium.
Does any metal start floating after some time?
  • Answer: Yes. Calcium.
Put the metals that did not react with cold water in beakers half-filled with hot water.

For the metals that did not react with hot water, arrange the apparatus as shown in Figure and observe their reaction with steam.


Which metals did not react even with steam?
  • Answer: Copper, Lead, Silver and Gold do not react with water or steam at all.
Arrange the metals in the decreasing order of reactivity with water.
  • Answer: Na > K > Ca> Mg > Al > Fe

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