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.)
Most abundant metal in the earth's crust is...............

Explanation

To solve the question, we need to fill in the blank with the appropriate word from the given options. The question asks for the most abundant metal in the Earth's crust.

1. **Identify the question**: The question is asking for the most abundant metal in the Earth's crust.

2. **Review the options**: The options provided are:
- gravity separation
- magnetic separation
- absence
...