Lesson: Metals and Non-metals
Exercise:

Question: 1

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

(b) Phosphorus

(d) Oxygen

Solution:

(a) Zinc

Question: 2

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.

Solution:

Question: 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.

Solution:

(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.

Question: 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. ( )

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

Solution:

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

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

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

Question: 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

Solution:

Properties	Metals	Non-metals
Appearance	Lustrous	Dull
Hardness	Hard	Soft
Malleability	Can be beaten into thin sheets	Cannot be beaten into thin sheets
Ductility	Can be drawn into wires	Cannot be drawn into wires
Heat conduction	Good conductor of heat	Poor conductor of heat
Conduction of electricity	Good conductor of electricity	Poor conductor of electricity

Question: 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.

Solution:

(a) Aluminium is a malleable metal and can be beaten into thin foils, which is used for wrapping food items.

(b) Metals are used as immersion rods for heating liquids because they are good conductors of heat and electricity.

(c) A more reactive metal displace a less reactive one from its salt, when the salt is dissolved in water. Since copper is less reactive than zinc, it cannot displace zinc from its salt solution.

Cu(s) + ZnSO₄ (aq) → No reaction

(d) Since sodium and potassium are highly reactive elements they are stored in kerosene. They can easily catch fire when in contact with air.

Question: 7

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

Solution:

Lemon pickle contains acids that reacts with aluminium and produces hydrogen gas. The pickle gets spoilt in this reaction. Thus, lemon pickle cannot be stored in aluminium utensils.

Question: 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 wire
(iii)	Aluminium	(c)	Wrapping food
(iv)	Carbon	(d)	Jewellery
(v)	Copper	(e)	Machinery
(vi)	Mercury	(f)	Fuel

Solution:

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

Question: 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.

Solution:

(a) There is no reaction when sulphuric acid is poured on a copper plate, because copper is less reactive than hydrogen present in sulphuric acid.
(b) Iron is more reactive than copper and therefore displaces copper in a copper sulphate solution. During this reaction, there is deposition of copper particles on the iron nails and also the blue colour of copper sulphate fades.

Iron (Fe) + Copper Sulphate (CuSO₄) → Iron Sulphate (FeSO₄) + Copper (Cu)

Question: 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.

Solution:

(a) Step 1: Add a few drops of water in the test tube containing the gas.

(b) Step 2: Put a lid on the test tube to cover it.

(d) Step 4: Test this solution with a blue and a red litmus paper.

Note: The blue litmus paper will turn red. This indicates that the gas is acidic.
(b) Charcoal reacts with oxygen and forms carbon dioxide gas.
C + O₂ → CO₂
(Carbon from Charcoal) + Oxygen → Carbon Dioxide
Carbon dioxide reacts with water to form carbonic acid. Carbonic acid turns the blue litmus paper into red.
CO₂ + H₂O → H₂CO₃
(Carbon Dioxide) + Water → (Carbonic Acid - turns blue litmus into red)

Question: 11

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?

Solution:

Gold ornament is dipped in a liquid called aqua regia (a mixture of hydrochloric acid and nitric acid) for polishing. When dipped in aqua regia, the outer layer of gold dissolves, revealing the inner shiny layer. When the outer layer dissolves, there is an automatic reduction of weight of the gold jewellery.