UPSC Civil Services Model Paper 4

Monazite is a reddish-brown phosphate mineral containing rare earth metals. It occurs usually in small isolated crystals.
Lanthanum is the most common rare earth element in monazite. So, statement 1 is correct.
Monazite is radioactive due to the presence of thorium and, less commonly, uranium.
Because of its radioactive nature, monazite is a useful for radiometric dating of geological events, such as crystallization, heating, or deformation of the rocks containing monazite. So, statement 2 is also correct.
Thorium extracted from Monazite sands can be used for generation of nuclear power.