Limestone is a naturally occuring form of calcium carbonate. It is used as building materials and also for manufacture of other building materials such as portland cement. It is used for the production of quickline and slaked lime which have wide applications in chemical, metallugical and construction industry. The pure `CaCO_(3)`, called precipitated calcium carbonate, is used extensively as filler, providing bulk to materials such as paint, plastics, printing links and rubber. it is also used in toothpastes, cosmetics and antacids. Quicklime and slaked lime are the cheapest and the most widely used bases for neutralising unwanted acids. Lime is used to neutralise acidic soils. An important application of quicklime is in air pollution control for the removal of `SO_(2)` in electric power plants. slaked lime is used in the manufature of other alkalis and bleacing powder, in sugar refinig, in tanning hide and in water softening.
The substance not likely to contain `CaCO_(3)` is

Options

A. Dolomite
B. A marble statue
C. Sea shells
D. Calcined gypsum

Explanation

To determine which substance is not likely to contain calcium carbonate (CaCO₃), we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the first option: Dolomite**
- Dolomite is a mineral composed of calcium magnesium carbonate, represented by the formula CaMg(CO₃)₂.
- Since it contains carbonate ions, it does contain CaCO₃ in its composition.

2. **Identify the second option: Marble statue**
- Marble is a metamorphic rock that primarily consists of calcite, which is a crystalline form of calcium carbonate (CaCO₃).
- Therefore, a marble statue does contain CaCO₃.

3. **Identify the third option: Sea shells**
- Sea shells are primarily made of calcium carbonate, which is often in the form of aragonite or calcite.
- Thus, sea shells also contain CaCO₃.

4. **Identify the fourth option: Calcium gypsum**
- Calcium gypsum, also known as gypsum, is primarily composed of calcium sulfate dihydrate, with the formula CaSO₄·2H₂O.
- This compound does not contain carbonate ions and therefore does not contain CaCO₃.

### Conclusion:
After analyzing all the options, the substance that is not likely to contain CaCO₃ is **Calcium gypsum** (option D).

### Final Answer:
**The substance not likely to contain CaCO₃ is Calcium gypsum (option D).**

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