Select the correct statements

(A) Crystalline solids have long range order.

(B) Crystalline solids are isotropic

(C) Amorphous solid are sometimes called pseudo solids.

(D) Amorphous solids soften over a range of temperatures.

(E) Amorphous solids have a definite heat of fusion.

Choose the most appropriate answer from the options given below.

What is A in the following reaction?

The correct sequence of correct reagents for the following transformation is :

The addition of silica during the extraction of copper from its sulphide ore :-