Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of

[A].	segar cones.
[B].	muffles for muffle furnaces.
[C].	insulating bricks.
[D].	crucibles used for melting of high purity metals.

Answer: Option D

Explanation:

No answer description available for this question. Let us discuss.