For making good quality mirrors, plates of float glass are used. These are obtained by floating molten glass over a liquid metal which does not solidify before glass. The metal used can be :

D and F Block Elements PYQ — JEE Main 2003 · Shift 0 · Q43 with Solution

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Correct answer: A

Identify the process mentioned

The question refers to the float glass process, where molten glass is floated over a molten metal to produce a very smooth, flat surface suitable for making high-quality mirrors.
Requirement for the metal

The liquid metal used must:
- remain molten while the glass spreads over it,
- have a high enough boiling point,
- be dense and non-reactive enough with glass,
- and importantly, not solidify before the glass.
Check the options
- A: Tin
  - Melting point of tin $\approx 232^\circ \text{C}$ .
  - In the float glass process, molten glass is indeed floated on molten tin.
  - This is the standard industrial method.
- B: Sodium
  - Very reactive metal.
  - Would react vigorously and is unsuitable.
- C: Magnesium
  - Also reactive and unsuitable for this purpose.
- D: Mercury
  - Mercury is liquid at room temperature, but it is not used in the float glass process for making float glass sheets.
  - Industrially, the process uses molten tin, not mercury.
Conclusion

The metal used is: $\boxed{\text{Tin}}$

So, the correct option is A.

View written solutionFree

Correct answer: A

Identify the process mentioned

The question refers to the float glass process, where molten glass is floated over a molten metal to produce a very smooth, flat surface suitable for making high-quality mirrors.
Requirement for the metal

The liquid metal used must:
- remain molten while the glass spreads over it,
- have a high enough boiling point,
- be dense and non-reactive enough with glass,
- and importantly, not solidify before the glass.
Check the options
- A: Tin
  - Melting point of tin $\approx 232^\circ \text{C}$ .
  - In the float glass process, molten glass is indeed floated on molten tin.
  - This is the standard industrial method.
- B: Sodium
  - Very reactive metal.
  - Would react vigorously and is unsuitable.
- C: Magnesium
  - Also reactive and unsuitable for this purpose.
- D: Mercury
  - Mercury is liquid at room temperature, but it is not used in the float glass process for making float glass sheets.
  - Industrially, the process uses molten tin, not mercury.
Conclusion

The metal used is: $\boxed{\text{Tin}}$

So, the correct option is A.