Question

Monazite is an ore of:
(A) Titanium
(B) Thorium
(C) Zirconium
(D) Iron

Answer 1

Hint: It is an ore of some rare earth minerals. The presence of this element caused monazite to be radioactive to some extent. Its main uses are in nuclear fuel applications.

Complete answer:
-First of all let us see what an ore is. An ore is a naturally occurring rock or solid material which contains one or more metals or valuable minerals that can be mined, extracted and treated profitably.
-A monazite is a reddish- brown coloured phosphate mineral which contains some rare earth elements. It is considered a group of minerals due to its varying composition. Monazite is also of 4 types based on the relative concentrations of the minerals.
-Mostly it contains thorium (Th), lanthanum (La), and cerium (Ce).
  Its molecular formula can be written as:$(Ce,La,Th)P{O_4}$
-It is usually found in the form of small isolated grains as an additional or accessory mineral in igneous and metamorphic rocks. It is often found in placer deposits. South Africa, Madagascar and India have large deposits of monazite sands.
Monazites are generally concentrated in the alluvial sands after being released from the weathering of pegmatite because of its high density.
-The presence of thorium and very small quantities of uranium causes monazite to be radioactive.

So, the correct option is: (B) Thorium.

Note: Do not think that monazite is totally radioactive like uranium. It possesses some radioactive properties due to the presence of thorium which is a lesser radioactive element. It contains phosphates and silicates of La, Ce, Th and Nd.