Materials Metals and Non Metals - Exemplar Solutions 1

CBSE Class 8 Science
NCERT Exemplar Solutions
Materials: Metals and Non-Metals

1. Which of the following is not a metal?
(a) copper
(b) sulphur
(c) aluminium
(d) iron
Ans. (b) Sulphur is not a metal because it is not hard, malleable, ductile or sonorous. In addition to this sulphur on reacting with oxygen produces Sulphur dioxide gives sulphurous acid whereas metallic oxides are basic in nature. Those Sulphur is non-metal.

2. The substance that will be flattened on beating with a hammer is
(a) crystal of iodine
(b) lump of sulphur
(c) piece of coal
(d) zinc granule
Ans. On beating with a hammer zinc granules will get flattened because it is a metal and hence prosses the property of malleability i.e. they can be beaten into thin sheets.

3. Boojho has learnt that non-metals on beating with a hammer are generally broken into pieces. Which of the following is a nonmetal?
(a) iron nail
(b) aluminium wire
(c) copper plate
(d) piece of coal
Ans. (d) piece of coal contains carbon which in turn is a non – metal and hence brittle and when beaten with hammer it turns into pieces.

4. Materials which can be drawn into wires are called ductile. Which of the following is not a ductile material?
(a) silver
(b) copper
(c) sulphur
(d) aluminium
Ans. (c) Ductility is to property of metals due to which metals can be drawn into him thin wires. Sulphur is non-metal and hence cannot be drawn into wires.

5. Metals are generally hard. Which of the following metals is an exception and can be cut with a knife?
(a) iron
(b) sodium
(c) gold
(d) magnesium
Ans. (b) Metals are hard and tough excepts sodium that can be cut with a knife.

6. Metals are generally solid. Which of the following metals is in the liquid state at room temperature?
(a) mercury
(b) silver
(c) aluminium
(d) sodium
Ans. (a) Metals are generally solid excepts mercury that is found in liquid state at room temperature.

7. Metals generally react with dilute acids to produce hydrogen gas. Which one of the following metals does not react with dilute hydrochloric acid?
(a) magnesium
(b) aluminium
(c) iron
(d) copper
Ans. (d) Copper does not react hydrochloric acid even on heating. It is highly unreactive metal.

8. Which of the following reacts with cold water vigorously?
(a) carbon
(b) sodium
(c) magnesium
(d) Sulphur
Ans. (b) Sodium react vigorously with water forming sodium hydroxide and hydrogen. To prevent this reaction, it is stored in kerosene.

9. The metal which produces hydrogen gas on reaction with dilute hydrochloric acid as well as sodium hydroxide solution is
(a) copper
(b) iron
(c) aluminium
(d) sodium
Ans. (c) Aluminium produces hydrogen gas on reaction with dilute hydrochloric acid is as follows:
Reaction of aluminium with sodium hydroxide solution is as follows:

10. Which of the following non-metals reacts and catches fire on exposure to air?
(a) phosphorus
(b) nitrogen
(c) sulphur
(d) hydrogen
Ans. (a) Phosphorus being a vigorously reacting non-metal catches fire if exposed to air. In order to avoid such reaction phosphorous is stored in water that disconnects its with atmospheric oxygen.

11. Generally metallic oxides are basic and non-metallic oxides are acidic in nature. Solution of which of the following oxides in water will change the colour of blue litmus to red?
(a) sulphur dioxide
(b) magnesium oxide
(c) iron oxide
(d) copper oxide
Ans. (a) Sulphur dioxide is a non-metal and as we know non-metallic oxides are acidic in nature. Therefore, Sulphur dioxide will change the blue litmus paper to red.

12. Which of the following property is not responsible for copper to be used as electrical conduction wires?
(a) ductility
(b) colour
(c) good conductor of electricity
(d) it is solid
Ans. (b) Copper being a metal is solid, possess the property of ductility and is a good conductor of electricity due to which it can be used as electrical conduction wires. Colour has nothing to do with it.