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Q: Expanded perlite is used as an insulating material. It is a chemically inert substance composed basically of ..............
  • A. limestone and rock salt
  • B. glass and calcium carbonate
  • C. silica and aluminium
  • D. asbestos and mica
Correct Answer: Option C - Expand perlite– Perlite is a volcanic rock containing from 2 to 5% bonded water. It is a chemically inert substance composed basically of silica and aluminium, but some impurities, such as Na₂O, CaO, MgO and K₂O which are hygroscopic can absorb moisture easily.
C. Expand perlite– Perlite is a volcanic rock containing from 2 to 5% bonded water. It is a chemically inert substance composed basically of silica and aluminium, but some impurities, such as Na₂O, CaO, MgO and K₂O which are hygroscopic can absorb moisture easily.

Explanations:

Expand perlite– Perlite is a volcanic rock containing from 2 to 5% bonded water. It is a chemically inert substance composed basically of silica and aluminium, but some impurities, such as Na₂O, CaO, MgO and K₂O which are hygroscopic can absorb moisture easily.