The correct order of acidity of hybrides of oxygen family

Options

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

Answer

To determine the correct order of acidity of the hydrides of the oxygen family (Group 16 elements), we need to analyze the stability of their conjugate bases. Here’s a step-by-step solution:

### Step 1: Identify the Hydrides
The hydrides of the oxygen family (Group 16) include:
- H₂O (water)
- H₂S (hydrogen sulfide)
- H₂Se (hydrogen selenide)
- H₂Te (hydrogen telluride)

### Step 2: Determine the Conjugate Bases
When these hydrides donate a proton (H⁺), they form their respective conjugate bases:
- From H₂O, the conjugate base is OH⁻ (hydroxide ion).
- From H₂S, the conjugate base is HS⁻ (hydrosulfide ion).
- From H₂Se, the conjugate base is HSe⁻ (hydroselenide ion).
- From H₂Te, the conjugate base is HTe⁻ (hydrogentelluride ion).

### Step 3: Analyze the Stability of Conjugate Bases
The acidity of a hydride is directly related to the stability of its conjugate base. The more stable the conjugate base, the stronger the acid.

#### Factors Affecting Stability:
1. **Electronegativity**: As we move down the group, the electronegativity decreases. This affects the ability of the atom to stabilize the negative charge.
2. **Atomic Size**: As we move down the group, the atomic size increases, allowing for better dispersion of the negative charge.

### Step 4: Order of Stability of Conjugate Bases
- HTe⁻ is the most stable due to the large atomic size of Te, which allows for better dispersion of the negative charge.
- HSe⁻ is next, as Se is larger than S and can also stabilize the negative charge well.
- HS⁻ follows, as S is smaller and less able to stabilize the negative charge compared to Se and Te.
- OH⁻ is the least stable because O is highly electronegative and does not disperse the negative charge effectively.

### Step 5: Order of Acidity
Since acidity is directly proportional to the stability of the conjugate base, the order of acidity of the hydrides is:
- H₂Te > H₂Se > H₂S > H₂O

### Final Answer
The correct order of acidity of the hydrides of the oxygen family is:
**H₂Te > H₂Se > H₂S > H₂O**