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Question
A solid substance P which is very hard is used in the construction of many buildings, especially flooring. When substance P is heated strongly, it decomposes to form another solid Q and a gas R is given out. Solid Q reacts with water with the release of a lot of heat to form a substance S. When gas R is passed into a clear solution of substance S, then a white precipitate of substance T is formed. The substance T has the same chemical composition as starting substance P.
- What is substance P? Write its common name as well as chemical formula.
- What is substance Q?
- What is gas R?
- What is substance S? What is its clear solution known as?
- What is substance T? Name any two natural forms in which substance T occurs in nature.
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Solution
- Substance P is calcium carbonate. Its common name is limestone, and its chemical formula is CaCO3.
- Substance Q is calcium oxide (CaO).
- Gas R is carbon dioxide gas (CO2).
- Substance S is calcium hydroxide [Ca(OH)2]. Its clear solution is known as lime water.
- Substance T is calcium carbonate (CaCO3). Two natural forms of calcium carbonate are calcite and mollusc shell.
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