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.)
Oxides ores are concentrated by ............... process.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the process used to concentrate oxide ores. We need to identify the correct term from the given options.

2. **Identifying the Process**: Oxide ores are typically concentrated using a method that relies on the physical properties of the ore. Among the options provided, we need to find the one that specifically relates to oxide ores.

3. **Choosing the Correct Term**: The process that is commonly used to concentrate oxide ores is known as "gravity separation." This method exploits the differences in density between the ore and the gangue (impurities).

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