The World of Metals and Non-metals

Correct Option: (i) Aluminium

Justification: Aluminium is cheap, lightweight, and highly malleable — meaning it can be beaten into very thin sheets (aluminium foil) that can be folded easily into any shape. It is therefore widely used for food packaging materials such as foil wraps and containers.

Correct Option: (iv) Sodium

Justification: Sodium is an extremely reactive metal. When it comes in contact with water, it reacts vigorously, generating a large amount of heat that is sufficient to catch fire. This is why sodium is stored in kerosene to prevent its exposure to moisture and air.

(i) False [F]
Reason: Aluminium and copper are metals, not non-metals. Metals are used for making utensils and statues because of their malleability, ductility, and lustrous appearance.

(ii) False [F]
Reason: Metals react with oxygen to form metal oxides, and these oxides are basic in nature. A basic solution turns red litmus paper to blue, not blue litmus paper to red. It is the oxides of non-metals that are acidic in nature and turn blue litmus red.

(iii) True [T]
Reason: Oxygen is indeed a non-metal (it is a non-metallic element). All living organisms require oxygen for the process of respiration to release energy from food. Without oxygen, survival is not possible.

(iv) False [F]
Reason: Copper vessels are used for boiling water because copper is a good conductor of heat, not electricity. Good thermal conductivity allows heat to transfer quickly and uniformly to the water inside the vessel.

Given: We need to explain why only a few metals are used for making jewellery.

Concept: Jewellery requires metals with specific properties.

Answer:
Only a few metals are suitable for making jewellery because jewellery requires metals that possess all of the following properties:

1. Lustrous appearance: The metal must be shiny and attractive. Metals like gold, silver, and platinum have a natural shine that makes jewellery look beautiful.

2. High malleability and ductility: The metal must be easily shaped into intricate designs and drawn into fine wires or thin sheets without breaking.

3. Resistance to corrosion: Jewellery is worn regularly and exposed to air, moisture, and sweat. The metal must not rust or tarnish easily. Gold and platinum do not corrode, making them ideal.

4. Non-reactivity: The metal should not react with skin, sweat, or common chemicals.

5. Rarity and value: Precious metals like gold and silver are rare, which adds to their value as jewellery.

Most common metals like iron rust easily, and many metals are not lustrous enough or are too brittle for jewellery making. Hence, only metals like gold, silver, and platinum are widely used for jewellery.

Step 1: Decode the jumbled names in Column II.

- (a) ENXYGO → OXYGEN
- (b) NECOHIRL → CHLORINE
- (c) PEPORC → COPPER
- (d) TENGOINR → NITROGEN
- (e) OGDL → GOLD

Step 2: Match with Column I.

| Column I | Column II |
|---|---|
| (i) Used in electrical wiring | (c) PEPORC → Copper |
| (ii) Most malleable and ductile | (e) OGDL → Gold |
| (iii) Living organisms cannot survive without it. | (a) ENXYGO → Oxygen |
| (iv) Plants grow healthy when fertilisers containing it are added to the soil. | (d) TENGOINR → Nitrogen |
| (v) Used in water purification | (b) NECOHIRL → Chlorine |

Reasoning:
- Copper is an excellent conductor of electricity, so it is used in electrical wiring.
- Gold is the most malleable and ductile of all metals.
- Oxygen is essential for respiration; living organisms cannot survive without it.
- Nitrogen is an essential nutrient for plant growth and is a key component of fertilisers.
- Chlorine is widely used in water purification to kill harmful microorganisms.

Given: Reactions of oxygen with magnesium (a metal) and sulfur (a non-metal).

Reaction 1: Magnesium with Oxygen

When magnesium ribbon is burned in air (oxygen), it burns with a dazzling white flame and forms magnesium oxide (a white powder).

$$\text{Magnesium} + \text{Oxygen} \rightarrow \text{Magnesium oxide}$$
$$2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}$$

When magnesium oxide is dissolved in water, it forms magnesium hydroxide, which is basic in nature. It turns red litmus paper blue.

$$\text{MgO} + \text{H}_2\text{O} \rightarrow \text{Mg(OH)}_2$$

Reaction 2: Sulfur with Oxygen

When sulfur is burned in air (oxygen), it burns and forms sulfur dioxide gas.

$$\text{Sulfur} + \text{Oxygen} \rightarrow \text{Sulfur dioxide}$$
$$\text{S} + \text{O}_2 \rightarrow \text{SO}_2$$

When sulfur dioxide dissolves in water, it forms sulfurous acid, which is acidic in nature. It turns blue litmus paper red.

$$\text{SO}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{SO}_3 \text{ (Sulfurous acid)}$$

Main Differences in the Nature of Products:

| Property | Magnesium Oxide (Metal oxide) | Sulfur Dioxide (Non-metal oxide) |
|---|---|---|
| Nature | Basic | Acidic |
| Effect on red litmus | Turns red litmus blue | No change (already red) |
| Effect on blue litmus | No change | Turns blue litmus red |

Conclusion: Oxides of metals (like magnesium oxide) are basic in nature, whereas oxides of non-metals (like sulfur dioxide) are acidic in nature.