Chapter 27 Metals and Non-metals Textbook Solutions

NIOS Class 10 Science Chapter 27 Question Answers

INTEXT QUESTIONS 27.1

1. Which properties of gold allow it to make ornaments?

Ans: Malleability and ductility

2. Name a few metals which are found in free state?

Ans: Gold, silver and platinum

3. Metals are generally very hard. Name the metal which is soft like wax?

Ans: Sodium

4. Name a non-metal which is a good conductor of electricity.

Ans: Graphite (an allotropic form of carbon)

5. Name two metals which show malleability and ductility.

Ans: Gold and aluminium

TERMINAL EXERCISES

1. Name two precious metals used in making ornaments and write names of two important properties of these metals.

Ans: Gold and Silver. They are most malleable and ductile. They also have poor reactivity when compared to other metals. 

2. Name two non-metals which are commonly available and name their two important properties.

Ans: 

• Hydrogen is used in the manufacturing of ammonia gas which is further used in the manufacturing of urea (fertiliser).
• Silicon is used in making transistors, chips for computers and photovoltaic cells.

3. Write four physical properties of metals.

Ans: 

• Metals are malleable.
• All the metals show metallic lustre.
• Metals are generally hard
• They exist in solid and liquid states
• Metals are sonorous and produce a characteristic metallic sound when struck
• High density
• Good conductor of electricity

4. Write four physical properties of non-metals.

Ans: 

• Non-metals are neither malleable nor ductile.
• They do not show any metallic lustre.
• Non-metals are soft in comparison to metals
• Non-metals exist in solid, liquid and gaseous states.
• They are non-sonorous
• Low density
• Bad conductor of electricity

5. How would you differentiate between a metal and a non-metal.

Ans: Metals can be distinguished from non-metals based on their physical properties like malleability, ductility, lustre, etc.

Metals	Non-metals
Metals are malleable.	Non-metals are neither malleable nor ductile.
All the metals show metallic lustre.	They do not show any metallic lustre.
Metals are generally hard	Non-metals are soft in comparison to metals
They exist in solid and liquid states	Non-metals exist in solid, liquid and gaseous states.
Metals are sonorous and produce a characteristic metallic sound when struck	They are non-sonorous
High density	Low density
Good conductor of electricity	Bad conductor of electricity

6. Write reaction of metals with the following:

(a) water (b) air or oxygen (c) acids

Ans: 

(a) Reaction of Metals with Water: Many metals react with water to form hydroxides. Hydroxides are basic in nature. Sodium and potassium react with cold water.

2Na(s) + 2H₂O(l) —→ 2NaOH(aq) + H₂(g)

(b) Reaction of metals with Oxygen: – Most of the metals react with oxygen and form oxides. The reaction may take place without heating as in sodium, calcium or potassium, while some metals react with oxygen on heating to form oxides. 

4Na(s) + O₂(g) —→ 2Na₂O(s)

(c) Reaction of metals with acids: – Metals react with common acids like dilute HCl and dilute H2SO4 with the evolution of H₂. The reaction of Mg ribbon with dil. HCl.

Mg(s) + 2HCl(aq) —→ MgCl₂(aq) + H₂(g)

7. What are three types of oxides of metals?

Ans: The three types of oxides of metals are

• Neutral oxides such as MgO, Na₂O
• Amphoteric oxides that can react with both acids and bases. Eg. Al₂O₃.
• Mixed oxides where the metal carries different oxidation states.

8. Name four uses of metals.

Ans: Uses of metals

• (i) Many metals like iron, copper and aluminium are used to make containers.
• (ii) Metals like copper, aluminium, iron and stainless steel are used to make utensils and frying pans.
• (iii) Ductile metals like copper and aluminium are used for making electrical wires. Steel ropes are used in cranes to lift heavy objects in the construction of bridges.
• (iv) Iron and steel are used to make machines
• (v) Zinc, lead, mercury, and lithium are used to make cells and batteries.
• (vi) Malleable metals like iron and aluminium are used to make sheets, which are used for various construction purposes.
• (vii) Gold, silver and platinum metals are used to make jewellery due to their lustre, high malleability and inert nature.
• (viii) Alloys of different metals and non-metals are used for various purposes e.g. Stainless steel for making utensils

9. Write four uses of non-metals.

Ans: Uses of non-metals

• (i) Hydrogen is used in the manufacturing of ammonia gas, which is further used in the manufacturing of urea (fertiliser).
• (ii) Hydrogen is a constituent of many industrial fuels like water gas ( CO + H₂) and coal gas (H₂ + CH₄).
• (iii) Silicon is used in making transistors, chips for computers and photovoltaic cells.
• (iv) Silicon is used in the steel industry to deoxidise steel, and it produces high-quality corrosion-resistant steel.
• (v) Most of the phosphorus is used for making phosphoric acid, H₃PO_4, which is used in the manufacturing of phosphate fertilisers.
• (vi) White phosphorus ( P₄S₃ ) is used in the match industry.
• (vii) Phosphates are added to the detergents as they help in the removal of dirt from soiled cloths.
• (viii)Sulphur is used in agriculture to control fungi and pests.
• (ix) Sulphur is used in the manufacturing of gun powder, which is an intimate mixture of sulphur, charcoal and potassium nitrate.
• (x) Most of sulphur is converted into sulphuric acid, which is called the king of chemicals and is used to make a variety of other chemicals.

10. Define the following:

(a) Brittleness (b) Sonorous nature.

Ans: 

• Brittleness is the tendency of a material to break easily. Such materials are not bendable or ductile. Non-metals are brittle and are not able to be moulded into desirable shapes.
• Sonorous nature is the ability of materials such as metals to produce a characteristic sound when struck. A school bell is a perfect example.

11. Name two metals which are most malleable and ductile. Also define:

(a) Malleability (b) Ductility

(c) Brittleness (d) Tensile nature

Ans:

Gold and silver are two metals that are the most malleable and ductile. 

• Malleability is the ability of metals to be as thin as possible when applied pressure. This is why metals are used for making sheets.
• Ductility is the ability of metals to be rolled and stretched thin to make thin materials such as wires.
• Brittleness is the tendency of a material to break easily. Such materials are not bendable or ductile.
• Tensile nature is the ability of materials to be stretched and pulled without breaking.

12. Write uses of the following metals:

(a) Pt (b) Au (c) Na (d) Ag (e) Ni

Ans: 

• Pt, Platinum: Used for making jewellery.
• Au, Aurum: Used in ornaments
• Na, Sodium: Used to make table salt, sodium chloride.
• Ag, Argentum: Used in jewellery
• Ni, Nickel: It is mixed with chromium to make stainless steel.

13. What is corrosion? How will you prevent it?

Ans: Corrosion is the oxidation of metals that could lead to the destruction of the metal surface, due to exposure to air and moisture. Some of the important methods of prevention of corrosion are as follows:

• 1. Painting: This is a common method of preventing iron from rusting. It prevents rusting by providing a coating over iron objects.
• 2. Oiling and greasing: To put a layer of oil and grease on the iron objects also prevents them from rusting. Iron parts of various machines and vehicles are oiled and greased to prevent rusting and to minimise friction.
• 3. Galvanisation: In this method, we put a layer of zinc metal on the iron objects, and this process is known as galvanisation. This method is used on a large scale for making galvanised iron sheets for making boxes and for roof covering.
• 4. Alloying: In this method, a particular metal with another metal or non-metal is mixed in a fixed proportion to improve its quality, like resistance towards corrosion, strength, hardness, shine and high tensile strength. For example, iron metal can not be used for making utensils because it will rust, but when it is mixed with nickel and chromium metal, it becomes stainless steel.

14. You are provided atomic number of metal X, Y and Z (not real names) in the following table. Based on electronic configuration predict whether they fall in the category of metal or non-metal.

Atomic number	Metal	Metal or non-metal
91216	XYZ	………….………….………….

Ans: Electronic configurations,

X: 9 – 2, 7 – Non-metal

Y: 12 – 2, 8, 2 – Metal

Z: 16 – 2, 8, 6 – Non-metal

15. Complete and balance the following reactions:

(i) Mg(s) + H₂SO₄(aq) –→ …………… + ……………

(ii) Fe(s) + H₂O(steam) –→ …………… + ……………

(iii) Na(s) + H₂O(l) –→ …………… + ……………

Ans: 

(i) Mg(s) + H₂SO₄(aq) → MgSO₄(aq) + H₂(g)

(ii) 3Fe(s) + 4H₂O(steam) → Fe₃O₄(s) + 4H₂(g)

(iii) 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

16. Write names and formulas of different oxides of nitrogen.

Ans: 

• (i) Nitrous oxide or laughing gas N₂O (neutral)
• (ii) Nitric oxide, NO (neutral)
• (iii) Dinitrogen trioxide, N₂O₃ (acidic)
• (iv) Nitrogen dioxide NO₂ (acidic)
• (v) Dinitrogen tetroxide, N₂O₄ (acidic)
• (vi) Dinitrogen pentoxide, N₂O₅ (acidic)

17. Which one of the following oxides is not acidic?

(a) CO 

(b) CO₂ 

(c) SO₂ 

(d) SO₃

Ans: (a) CO, carbon monoxide, is the neutral oxide. 

18. Write at least one important use of the following chemicals

(a) H₃PO₄ (b) H₂SO₄ (c) NH₃ (d) Water gas

Ans: 

• (a) H₃PO₄: Manufacture phosphate fertilisers
• (b) H₂SO₄: King of chemicals, used for making a variety of other chemicals
• (c) NH₃: Used in the manufacture of urea.
• (d) Water gas: Industrial fuel

19. Identify the non-metal from the following which is used for fungus control in agriculture:

(a) Phosphorus 

(b) Sulphur 

(c) Iodine

Ans: (b) Sulphur

20. Which of the following metals is not used in making cell/battery?

(a) Zn 

(b) Pb 

(c) Hg 

(d) Na

Ans: (d) Na

21. Which of the following non-metals is a liquid at room temperature

(a) Bromine 

(b) Phosphorus 

(c) Sulphur 

(d) Iodine

Ans: (a) Bromine

22. Complete the following reactions

(i) Al₂O₃(s) + …………. –→ 2NaAlO₂ (Sodium aluminate) + H₂O(l)

(ii) CaO(s) + …………. –→Ca(OH)₂

(iii) Sn(s) + ………….+ H₂O(l) –→ Na₂SnO₃ (Sodium stannate)

Ans: 

(i) Al₂O₃(s) + 2NaOH (aq) –→ 2NaAlO₂ (Sodium aluminate) + H₂O(l)

(ii) CaO(s) + H₂O–→Ca(OH)₂

(iii) Sn(s) + 2NaOH(aq)  + H₂O(l) –→ Na₂SnO₃ (Sodium stannate)

23. Define Roasting and Calcination.

Ans: 

• Roasting: Heating an ore in the presence of an excess supply of air or oxygen.

2ZnS(s) + 3O₂(g) —→ 2ZnO(g) + 2SO₂(g)

• Calcination: Heating an ore in the absence of a limited supply of air.

ZnCO₃(s) —→ ZnO(s) + CO₂(g)

Additional Study Materials

• Chapter 1 Measurement in Science and Technology
• Chapter 2 Matter in our Surroundings
• Chapter 3 Atoms and Molecules
• Chapter 4 Chemical Reaction and Equations
• Chapter 5 Atomic Structure
• Chapter 6 Periodic Classification of Elements
• Chapter 7 Chemical Bonding
• Chapter 8 Acids, Bases, and Salts