Acidity of diprotic acids in aqueous solutions increases in the order

Options

A. `H_(2)S lt H_(2)Se lt H_(2) Te`
B. `H_(2)Se lt H_(2)S lt H_(2)Te`
C. `H_(2)Te lt H_(2)S lt H_(2)Se`
D. `H_(2)Se lt H_(2)Te lt H_(2)S`

Explanation

To determine the order of acidity of diprotic acids in aqueous solutions, we need to analyze the trend in acidity as we move down the group of the chalcogens (Group 16 elements) in the periodic table. The diprotic acids we will consider are H2O, H2S, H2Se, H2Te, and H2Po.

### Step-by-Step Solution:

1. **Understanding Diprotic Acids**:
- A diprotic acid is capable of donating two protons (H⁺ ions) in an aqueous solution. Examples include H2S, H2Se, H2Te, etc.

2. **Identifying the Group**:
- The relevant group for this question is Group 16, which contains the elements: Oxygen (O), Sulfur (S), Selenium (Se), Tellurium (Te), and Polonium (Po).

3. **Analyzing Atomic Size**:
- As we move down the group from oxygen to polonium, the atomic size increases due to the addition of electron shells. This increase in size affects the bond lengths and bond strengths of the H-X bonds (where X is the chalcogen).

4. **Bond Strength and Acidity Relationship**:
- The bond dissociation enthalpy (the energy required to break the bond) decreases as the size of the central atom increases. This means that the H-X bond becomes weaker down the group.

5. **Acidity Trend**:
- Weaker bonds are easier to break, which means that the tendency of the acid to donate protons increases. Therefore, the acidity of diprotic acids increases down the group.
- The order of acidity in aqueous solutions is:
- H2O < H2S < H2Se < H2Te < H2Po

6. **Conclusion**:
- Based on the analysis, the acidity of diprotic acids increases in the order: H2O < H2S < H2Se < H2Te < H2Po. This corresponds to the increasing size of the central atom and the decreasing bond strength.

### Final Order of Acidity:
- **H2O < H2S < H2Se < H2Te < H2Po**