Chapter 3. Metals and Non-Metals

Class 10 Science Chapter 3. Metals and non-Metals Internal Questions and Answers 

INTERNAL QUESTIONS

1. Give an example of a metal which
(i) is a liquid at room temperature.
(ii) can be easily cut with a knife.
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat.

Answer :  (i) Mercury .

(ii) Sodium (Potassium and lithium) .

(iii) Silver (or Copper) .

(iv) Lead (Mercury) .
2. Explain the meanings of malleable and ductile.

Answer : Malleable : Some metals can be beaten into thin sheets .This property is called malleability of malleable . Example : Gold and silver are the most malleable metals .

Ductile :The ability of metals to be draw into thin wires is called ductility or ductile . Example : Gold is the most ductile metal .

INTERNAL QUESTIONS

1. Why is sodium kept immersed in kerosene oil?

Answer : Sodium is the most reactive metal. It is vigorously catching fire when kept in the open in the air. So, Sodium kept immersed in kerosene oil.
2. Write equations for the reactions of
(i) iron with steam
(ii) calcium and potassium with water

Answer :  (i) When iron react with steam then produce iron oxide and  hydrogen gas .

    
(ii) When calcium react with water then produce calcium hydroxide and hydrogen gas .

        

 When potassium with water then produce potassium hydroxide and hydrogen gas .

      
3. Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.

Metal	Iron(II) Sulphate	Copper (II) Sulphate	Zinc Sulphate	Silver nitrate
A	No reaction	Displacement
B	Displacement		No reaction
C	No reaction	No reaction	No reaction	Displacement
D	No reaction	No reaction	No reaction	No reaction

Use the Table above to answer the following questions about metals A, B, C and D.
(i) Which is the most reactive metal?
(ii) What would you observe if B is added to a solution of Copper(II) sulphate?
(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

Answer:  (i) B is the most reactive metal .

(ii) If B is added to a copper sulphate (II) solution, then B has displaced or removed another copper component from the copper sulphate (II) solution.

(iii)  B  > A > C > D .
4. Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute  .

Answer: When dilute hydrochloric acid is added to a reactive metal then produce salt and hydrogen gas .

         Metal + Dilute → Salt + Hydrogen gas .

When iron reacts with dilute  then produce iron(II) sulphate and hydrogen gas .

      
5. What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.

Answer: When zinc is added to a solution of iron(II) sulphate then produce zinc sulphate

  

INTERNAL QUESTIONS

1. (i) Write the electron-dot structures for sodium, oxygen and magnesium.
(ii) Show the formation of  and  by the transfer of electrons.
(iii) What are the ions present in these compounds?

Answers:  (i) The electron-dot structures for sodium :

Atomic number of Na is 11

Electronic Configuration of Na is 2.8.1

                 

The electron-dot structures for oxygen :

Atomic number of O is 8

Electronic Configuration of O is 2.6

               

The electron-dot structures for magnesium :

Atomic number of Mg is 12

Electronic Configuration of Mg is 2.8.2

                  

(ii)  Formation of  by the transfer of electrons:

  : Atomic number of Na is 11

Electronic Configuration of Na is 2.8.1

Atomic number of O is 8

Electronic Configuration of Na is 2.6

Formation of  by the transfer of electrons:

 : Atomic number of Mg is 12

Electronic Configuration of Mg is 2.8.2

Atomic number of O is 8

Electronic Configuration of O is 2.6

(iii) Ions present in these compounds:

In  , the ions present are  (sodium ion) and  (oxide ion).

In , the ions present are   (magnesium ion) and  (oxide ion).

2. Why do ionic compounds have high melting points?

Answer: Ionic compounds have high melting points. This is because a considerable amount of energy is needed to break the strong inter-ionic attraction.

INTERNAL QUESTIONS

1. Define the following terms.
(i) Mineral        (ii) Ore         (iii) Gangue

Answer: (i) Mineral : Elements or compounds naturally present on the Earth's crust are called minerals.

(ii) Ore : In certain places, minerals contain a very high percentage of a particular metal and the metal can be extracted profitably. These minerals are called ores.

(iii) Gangue : Minerals extracted from the ground are usually contaminated with large amounts of impurities such as soil, sand, etc., called gangue.
2. Name two metals which are found in nature in the free state.

Answer: gold and silver .
3. What chemical process is used for obtaining a metal from its oxide?

Answer: Reduction process .

INTERNAL QUESTIONS

1. Metallic oxides of zinc, magnesium and copper were heated with the following metals.

Metal	Zinc	Magnesium	Copper
Zinc oxide
Magnesium
Copper oxide

 In which cases will you find displacement reactions taking place?

Answer: 

Metal	Zinc	Magnesium	Copper
Zinc oxide	------	Displacement reaction	------
Magnesium oxide	-----	------	------
Copper oxide	Displacement reaction	Displacement reaction	-----

2. Which metals do not corrode easily?

Answer: Some metals are found in the earth’s crust in the free state . This type of metal can not be  easily corroded. For example:  gold, silver, platinum and copper .
3. What are alloys?

Answer: An alloy is a homogeneous mixture of two or more metals, or a metal and a non-metal.

Class 10 Science Chapter 3. Metals and non-Metals Exercise Questions and Answers :

1. Which of the following pairs will give displacement reactions?
(a) NaCl solution and copper metal
(b)   solution and aluminium metal
(c)  solution and silver metal
(d)  solution and copper metal.

Answer: (d)   solution and copper metal.
2. Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) All of the above.

Answer: (c) Applying a coating of zinc .
3. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
(a) calcium
(b) carbon
(c) silicon
(d) iron.

Answer: (a) Calcium .
4. Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin.
(b) zinc has a higher melting point than tin.
(c) zinc is more reactive than tin.
(d) zinc is less reactive than tin.

Answer: (c) zinc is more reactive than tin.
5. You are given a hammer, a battery, a bulb, wires and a switch.
(a) How could you use them to distinguish between samples of metals and non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.

Answer : (a) Connect the bulb, battery, switch, and wires to create a simple electrical circuit. Then, touch the metal samples to see if they complete the circuit and light up the bulb. Metals conduct electricity and will light up the bulb, while non-metals won't .

(b) This test is useful for distinguishing between metals and non-metals as it relies on the conductivity of materials. Metals conduct electricity, allowing the circuit to be completed and the bulb to light up, while non-metals do not conduct electricity, preventing the bulb from lighting up .

6. What are amphoteric oxides? Give two examples of amphoteric oxides.

Answer: The metal oxides which react with both acids as well as bases to produce salts and water are called amphoteric oxides.  Example :  and  (Sodium aluminate) .
7. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Answer:  Magnesium and aluminium are two metals that will replace hydrogen with dilute acids. Copper and gold are two metals that cannot replace hydrogen in diluted acids.

8. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Answer : In the electrolytic refining of metal M, the anode is made of impure metal M, the cathode is a pure metal M electrode, and the electrolyte is a solution of a compound containing metal M ions.
9. Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.
(a) What will be the action of gas on
(i) dry litmus paper?
(ii) moist litmus paper?
(b) Write a balanced chemical equation for the reaction taking place.

Answer :  (a) The action of the gas on litmus paper: (i) Dry litmus paper: The gas collected by Pratyush is sulphur dioxide (). It is an acidic gas that will turn blue litmus paper red.

(ii) Moist litmus paper: Sulphur dioxide () dissolves in water to form sulphurous acid (). Sulphurous acid is acidic and will turn blue litmus paper red as well.

(b) Balanced chemical equation for the reaction:

S (sulphur) +   (oxygen) →  (sulphur dioxide)

10. State two ways to prevent the rusting of iron.

Answer:  There are two ways to prevent the rusting of iron :

(i) Galvanisation is a method of protecting steel and iron from rusting by coating them with a thin layer of zinc.

(ii) Alloying is a very good method of improving the properties of a metal.

11. What type of oxides are formed when non-metals combine with oxygen?

Answer : When non-metals combine with oxygen, they typically form acidic oxides.
12. Give reasons
(a) Platinum, gold and silver are used to make jewellery.
(b) Sodium, potassium and lithium are stored under oil.
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Answer: (a) Platinum, gold and silver are used to make jewellery. It is because of their malleability and ductility that metals can take various forms depending on our needs .

(b) Because sodium, potassium and lithium are most reactive metals so that these kinds of metals react vigorously that they catch fire if held in the open air. Therefore, to protect them from accidental fires, they are kept the oil

(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking . Because metals are good heat conductors with high melting points.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction. Because it is easier to get a metal from its oxide instead of its sulphides and carbonates.

13. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

Answer :  Lemon and tamarind juice are effective in cleaning tarnished copper vessels because they contain acids that react with the tarnish (copper oxide). The acid breaks down the tarnish, making it soluble in water. When we scrub or rinse the vessel with the juice, it removes the tarnish, restoring the vessel's shine.
14. Differentiate between metal and non-metal on the basis of their chemical properties.

Answers: Difference between metal and non-metal on the basis of their chemical properties are :

Metal	Non-metals
(i) Metals react with oxygen and form metallic oxide . Example :  ,,.. etc.	(i) Non-metals react with oxygen and form non-metallic oxides. Example : ,  , , etc.
(ii) When metals react with water, then produce metal hydroxide and hydrogen gas.  Metal + Water  Metal hydroxide + Hydrogen	(ii) Non-metals do not react with water .
(iii) When metals react with acids, then produce salt and hydrogen gas.    Metal + Dilute acid  Salt + Hydrogen	(iii) Non-metal do not react with dilued acid .

15. A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Answer: The solution the man used to clean the gold bangles was likely a strong acid, such as Aqua Regia. The acid dissolved some of the gold, leading to the reduction in weight.

16. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).

Answer : Copper is used for hot water tanks over steel due to its superior malleability, excellent heat conductivity, and high melting point. Additionally, copper does not react with water, ensuring durability and efficient heat transfer for hot water applications.