Question

Identify the correctly matched pairs.

1. \(\mathrm{TiO_2}\) – Pigment industry
2. \(\mathrm{MnO_2}\) – Dry battery cells
3. \(\mathrm{Cu/Ni}\) alloy – UK 'copper' coins

• A. \( \text{ii, iii, i} \)
• B. \( \text{ii, iii only} \)
• C. \( \text{i, ii only} \)
• D. \( \text{i, iii only} \)

Hint:

When dealing with industrial uses of chemicals or alloys, make sure to focus on common applications in consumer products or industry standards.

Answer 1

The Correct Option is C

- TiO\(_2\) is widely used in the pigment industry due to its high refractive index and strong opacity. - MnO\(_2\) is commonly used in dry battery cells like alkaline batteries as a depolarizer. - Cu/Ni alloy, often referred to as 'cupro-nickel,' is used in the production of UK 'copper' coins, although they primarily consist of this alloy instead of pure copper. Thus, the correct matching pairs are (i) and (ii), making option (3) the correct answer.

Answer 2

Step 1: Understanding the Uses of Each Compound
- Titanium dioxide (\(\mathrm{TiO_2}\)) is widely used in the pigment industry due to its brilliant white color and high refractive index. It is a common white pigment in paints, plastics, and cosmetics.

- Manganese dioxide (\(\mathrm{MnO_2}\)) is used as a depolarizer in dry battery cells (especially alkaline and Leclanché cells). It helps in preventing the buildup of hydrogen gas, allowing the battery to function efficiently.

- Copper-nickel alloy (Cu/Ni) is used for making coins in many countries, but the UK 'copper' coins are not made from this alloy; historically, UK coins have had different compositions, often copper-plated steel or bronze alloys.

Step 2: Evaluating the Matching Pairs
Based on the above:
(i) \(\mathrm{TiO_2}\) – Pigment industry: Correct
(ii) \(\mathrm{MnO_2}\) – Dry battery cells: Correct
(iii) \(\mathrm{Cu/Ni}\) alloy – UK 'copper' coins: Incorrect

Step 3: Conclusion
Therefore, only pairs (i) and (ii) are correctly matched.