Which of these structures could be Metal? *
2, 8, 2
2, 8, 8
2, 8, 4
Answers
Answer:
2,8,2
Explanation:
The elements which have tendency to lose electrons are called metals. They have less than 4 electrons in their outermost shell. Magnesium (Mg-2,8,2) has less than 4 electrons in outermost shell and hence is a metal
Answer:
Metals And Non Metals
NCERT Exemplar solution for Class 8 Science Chapter 4 Materials Metals and Non-Metals is the best study material you can utilise for effective exam preparation of Class 8 and competitive examinations. NCERT exemplar boosts your confidence by providing extra knowledge. After studying Exemplar question you will be able to solve all varieties of questions you get in the examination.
NCERT Exemplar Solutions for Class 8 Science Materials Metals and Non-Metals presented here has answers to 12 Multiple choice questions, 9 very short answer questions, 6 short answer questions, and 5 long answer questions.
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Multiple Choice Questions
1. Which of the following is not a metal?
(a) Copper
(b) Sulphur
(c) Aluminium
(d) Iron
Soln:
Answer is (b) Sulphur
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
Soln:
Answer is (d) zinc granule
Explanation:
Metals can be beaten into thin sheets whereas non-metals break into pieces on hitting hence answer is (d) zinc granule.
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) Copperplate
(d) Piece of coal
Soln:
Answer is (d) Piece of coal
Explanation:
Iron, Copper and aluminium are metals whereas coal is a non-metal hence answer is (d) piece of coal.
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
Soln:
Answer is (c) sulphur
Explanation:
Ductility is the property of metals. Here Sulphur is non-metal which is not have ductile property.
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
Soln:
Answer is (b) Sodium
Explanation:
Sodium is highly reactive metals which looks soft and can be cut into pieces by using 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
Soln:
Answer is (a) Mercury
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
Soln:
Answer is (d) Copper
Explanation:
Less reactive metals like Copper, gold and silver does not react with dilute HCl to produce Hydrogen gas.
8. Which of the following reacts with cold water vigorously?
(a) Carbon
(b) Sodium
(c) Magnesium
(d) Sulphur
Soln:
Answer is (b) Sodium
Explanation:
Sodium reacts vigorously with water, hence it is stored in kerosene to avoid reaction of sodium with moisture in the atmosphere and oxygen.
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
Soln:
Answer is (c) Aluminium
Explanation:
Aluminium reacts with dilute HCl as well as NaOH to produce Hydrogen Gas.
10. Which of the following non-metals reacts and catches fire on exposure to air?
(a) Phosphorus
(b) Nitrogen
(c) Sulphur
(d) Hydrogen
Soln:
Answer is (a) Phosphorus
11. Generally, metallic oxides are basic and non-metallic oxides are acidic in nature. The 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
Soln:
Answer is (a) Sulphur dioxide
Explanation:
Sulphur forms Sulphur-di-oxide which is acidic in nature and it will convert blue litmus 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
Soln:
Answer is (b) Colour.
Very Short Answer Questions
13. Name two soft metals which can be cut with a knife.
Soln:
(i) Sodium (ii) Potassium
14. Which non-metal is essential for our life and all living beings inhale it during breathing?
Soln:
Oxygen.
15. Name two major non-metals which are present in fertilisers and enhance the growth of plants.
Soln:
(i)Nitrogen (ii) Phosphorus
16. Which non-metal is used to disinfect water?
Soln:
Chlorine.