Explanation: Kerala, a state in southern India, is known for its rich mineral deposits, particularly monazite and thorium. The coastal sands of Kerala are a significant source of these minerals, which are of great economic and industrial importance.
Monazite is a rare earth mineral that is primarily composed of phosphate of several rare earth elements, including thorium. It is found in placer deposits, which are formed by the concentration of heavy minerals in sediments due to the action of water. The coastal regions of Kerala, especially the beaches and river mouths, are rich in these placer deposits, making Kerala one of the leading sources of monazite in India.
Thorium, a radioactive element, is a byproduct of monazite. It is used in nuclear energy, particularly in the production of nuclear fuel. Thorium is also used in various industrial applications, such as in the production of ceramics, glass, and refractory materials. The presence of thorium in monazite makes it a valuable resource for both energy and industrial purposes.
The other minerals mentioned in the options are not as significant in Kerala. Gypsum, a sulfate mineral, is more commonly found in other parts of India, such as Rajasthan and Gujarat. Bauxite, an aluminum ore, is more prevalent in states like Orissa and Gujarat. Granite, while present in Kerala, is not as economically significant as monazite and thorium.
In summary, the correct answer is (A) Monazite and thorium, as these are the minerals most closely associated with Kerala's mineral resources. The coastal sands of Kerala are a significant source of these minerals, which are of great economic and industrial importance due to their rare earth elements and radioactive properties. Understanding the mineral resources of Kerala is crucial for comprehending the state's economic and industrial landscape, as well as its contribution to India's mineral wealth.