To protect broken bones, Plaster of Paris is used. It is:
- ASlaked lime
- BCalcium carbonate
- CCalcium oxide
- DGypsum
- ENone of the above/More than one of the above
Show answer and explanation
Correct answer: (d) Gypsum
Explanation
Plaster of Paris is made by heating gypsum, CaSO₄·2H₂O, to about 120 °C, which drives off part of its water:
CaSO₄·2H₂O → CaSO₄·½H₂O + 1½H₂O
Mixed with water, it turns back into hard gypsum, which is why it is used to set broken bones, for casts and for moulds. Of the options, gypsum is its source mineral.