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Materials : Metals and Non-metals (Chemistry) Class 8 - NCERT Questions
Q 1.

Which of the following can be beaten into thin sheets?
(A) Zinc
(B) Phosphorus
(C) Sulphur
(D) Oxygen

SOLUTION:

(A) Generally metals are malleable.

Q 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:

(C) Generally metals are malleable and ductile.

Q 3.

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.

SOLUTION:

(A) reactive (B) good, electricity (C) more (D) hydrogen

Q 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.

SOLUTION:

(A) F (B) T (C) F (D) F

Q 5.

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

SOLUTION:

Q 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:

Aluminium is metal (i.e., malleable), soft and does not react with food materials.
Therefore aluminium foils are used to wrap food items.
(B) Metals are good conductor of heat and electricity. So immersion rods are made of metallic substance.
(C) Copper is less reactive than zinc. Therefore copper cannot displace zinc from its salt solution.
(D) Sodium and potassium react most vigorously with the oxygen in air to form their oxides. Therefore sodium and potassium are stored in kerosene.

Q 7.

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

SOLUTION:

No, we cannot store the lemon pickle in aluminium utensil because, aluminium is a metal and lemon is acid. The acids react with aluminium to release hydrogen which would spoil the food and render it unfit for use.

Q 8.

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 the uses in column II.

SOLUTION:

Q 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:

Q 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) When charcoal burnt then carbon dioxide gas is formed. This gas turns lime water into milky substance. It can also be tested by red and blue litmus. The solution of gas turns blue litmus into red so it is acidic.
(B) Carbon + oxygen → carbon dioxide Carbon dioxide + lime water → milky

Q 11.

One day Reeta went to a Jeweller’s shop with her mother. Her mother gave an 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 is metal it is washed in acidic solution. Some gold dissolve in acid to form oxide. This causes the loss of gold in the form of gold oxide. In this process certain amount of gold is lost to the acidic solution.