Which of the following is a form of calcium carbonate?

Correct option is C

The correct answer is (c) Limestone

Explanation:

• Limestone is a sedimentary rock composed primarily of calcium carbonate ($CaCO_3$) in the form of the mineral calcite.

• It is widely found in nature and is formed through the accumulation of shell, coral, algal, and fecal debris in marine environments.

• In chemistry, calcium carbonate exists in various natural forms, including chalk, marble, and limestone; all share the same chemical formula.

• When heated strongly, limestone undergoes thermal decomposition to produce quicklime (calcium oxide) and carbon dioxide.

• According to NCERT Class 10 Science, calcium carbonate is the primary constituent of eggshells and sea shells as well.

Information Booster:

• Calcium carbonate is used extensively in the construction industry as a building material and as an essential ingredient in the manufacture of cement.

• In medicine, it is commonly used as an antacid to relieve heartburn and as a calcium supplement to treat osteoporosis.

Additional Knowledge:

Washing Soda (Option a)

• Its chemical name is Sodium Carbonate ($Na_2CO_3 \cdot 10H_2O$).

• It is used as a cleaning agent for domestic purposes and for removing the permanent hardness of water.

Baking Soda (Option b)

• Its chemical name is Sodium Hydrogen Carbonate or Sodium Bicarbonate ($NaHCO_3$).

• It is primarily used in baking to make cakes and bread fluffy and as a mild antiseptic.

Table Salt (Option d)

• Its chemical name is Sodium Chloride ($NaCl$).

• It is a common salt used in food and is a fundamental raw material for producing various chemicals like sodium hydroxide and bleaching powder.