The different stages of preparing amorphous silicon are given below.
I. Silica is finely powdered.
II. The product is washed with hydrochloric acid.
III. The mixture of powdered silica and magnesium is heated in a fire-clay crucible.
IV. The product is washed with hydrofluoric acid to remove unchanged silica.
The correct arrangement of the above stages is :
- I, III, II and IV
- I, II, III and IV
- IV, I, II and III
- I, IV, III and II