______ores are concentrated by froth flotation and roasted in excess of air to convert them into their respective ______.

Answer

To solve the question, we need to fill in the blanks with the appropriate terms related to the concentration and roasting of ores.

### Step-by-Step Solution:

1. **Identify the first blank**: The question states that certain ores are concentrated by the froth flotation method. The froth flotation method is specifically used for concentrating ores that are light in weight and often contain sulfide minerals. Therefore, the first blank can be filled with "sulfide".

**First Blank**: Sulfide

2. **Identify the second blank**: The question then mentions that these ores are roasted in excess of air to convert them into their respective products. When sulfide ores are roasted, they typically convert into metal oxides. Thus, the second blank can be filled with "oxides".

**Second Blank**: Oxides

### Final Answer:
Sulfide ores are concentrated by froth flotation and roasted in excess of air to convert them into their respective oxides.

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