The pair that does NOT require calcination is :

Options

A. 1.`Fe_(2)O_(3)` and `Ca_(2)CO_(3).MgCO_(3)`
B. 2.`ZnCO_(3)` and `CaO`
C. 3.`ZnO` and `Fe_(2)O_(3).xH_(2)O`
D. 4.`ZnO` and `MgO`

Explanation

To solve the question regarding which pair does NOT require calcination, we first need to understand what calcination is and when it is used.

### Step-by-Step Solution:

1. **Understanding Calcination**:
- Calcination is a thermal treatment process in the presence of air or oxygen. It is primarily used to remove volatile substances from ores, convert carbonates to oxides, and drive off water from hydrated minerals.
- It is mainly applied to carbonate ores (like zinc carbonate) and hydrated ores (like hydrated aluminum oxide).

2. **Analyzing the Options**:
- **Option 1**: Ferrous oxide (FeO) and another compound (not specified).
- Since ferrous oxide is already an oxide, it does not require calcination.
- **Option 2**: Zinc carbonate (ZnCO₃) and calcium oxide (CaO).
- Zinc carbonate requires calcination to convert it to zinc oxide (ZnO), but calcium oxide is already an oxide, so this option is partially correct.
- **Option 3**: Zinc oxide (ZnO) and ferrous oxide (FeO).
- Both are already oxides, so they do not require calcination.
- **Option 4**: Zinc oxide (ZnO) and magnesium oxide (MgO).
- Both are oxides and do not require calcination.

3. **Conclusion**:
- The pairs that do NOT require calcination are those that consist of oxides. Therefore, the correct answer is any option that contains only oxides.
- Based on the analysis, **Option 1**, **Option 3**, and **Option 4** do not require calcination. However, since the question asks for a pair, we can conclude that **Option 3** (Zinc oxide and Ferrous oxide) is the most straightforward answer, as both are oxides.

### Final Answer:
The pair that does NOT require calcination is **Zinc oxide and Ferrous oxide**.