Fill in the blanks choosing appropriate word/ words from those given in the brackets : (gravity separation, magnetic separation, absence, presence, `CuFeS_2`, `Cu_2S`, froth flotation, aluminium, iron, smelting, pure, impure, mines, copper, silver, sulfide, zinc, chromium nickel, tin, blister copper, Cus, Fes, thermal, electrical, argentite or silver glance `(Ag_2S)`, cuprous oxide, cuprous sulfide.)
During bessemerisation......and......react to form metallic copper.

Explanation

**Step-by-Step Solution:**

1. **Understanding Bessemerization**: Bessemerization is a metallurgical process used to convert copper sulfide ores into metallic copper. This process involves blowing air into molten copper.

2. **Identifying the Reactants**: In the Bessemerization process, the two key reactants involved are copper(I) sulfide (Cu₂S) and copper(I) oxide (Cu₂O).

3. **Chemical Reactions**: During Bessemerization, Cu₂S is partially oxidized by the air blast to form Cu₂O. The reaction can be summarized as:
- Cu₂S + O₂ → Cu₂O + SO₂ (sulfur dioxide)
...