If an element X forms an oxide `X_(2)O_(3)`, then find the group in Mendeleev's periodic table where it is placed

Options

A. group III
B. group V
C. group VII
D. group VIII

Explanation

To determine the group in Mendeleev's periodic table where the element X is placed, based on the oxide it forms (X₂O₃), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Oxide Formula**: The given oxide is X₂O₃. This indicates that two atoms of element X combine with three atoms of oxygen.

2. **Determine the Valency of Oxygen**: Oxygen typically has a valency of -2, meaning it can gain two electrons to achieve a stable electronic configuration.

3. **Calculate the Total Charge from Oxygen**: Since there are three oxygen atoms in the formula X₂O₃, the total negative charge contributed by oxygen is:
\[ 3 \times (-2) = -6 \]

4. **Determine the Charge of Element X**: To balance the -6 charge from the three oxygen atoms, the total positive charge from the two X atoms must be +6. Therefore, each X atom must have a charge of:
\[ \frac{+6}{2} = +3 \]

5. **Establish the Valency of Element X**: Since each atom of X has a charge of +3, we conclude that the valency of element X is +3.

6. **Relate Valency to Group Number**: In Mendeleev's periodic table, the group number corresponds to the valency of the element. Since the valency of X is +3, it belongs to Group 3.

7. **Conclusion**: Therefore, element X is placed in Group 3 of Mendeleev's periodic table.

### Final Answer:
Element X is placed in Group 3 of Mendeleev's periodic table.

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