`H_(2)O` is liquid and `H_(2)S` is a gas because -

Options

A. Oxygen form stronger hydrogen bond than sulphur
B. Oxygen is less electronegative than sulphur
C. Atomic radius of oxygen is less than that of sulphur
D. Atomic radius of oxygen is greter than that of sulphur

Answer

To understand why \( H_2O \) (water) is a liquid while \( H_2S \) (hydrogen sulfide) is a gas, we need to analyze the molecular interactions and bonding in both substances. Here’s a step-by-step breakdown:

### Step 1: Molecular Structure
Both \( H_2O \) and \( H_2S \) are composed of two hydrogen atoms bonded to a central atom (oxygen in water and sulfur in hydrogen sulfide).

### Step 2: Electronegativity
Oxygen is more electronegative than sulfur. This means that in \( H_2O \), the oxygen atom pulls the shared electrons closer to itself, creating a polar molecule with a significant dipole moment. In contrast, \( H_2S \) has a less polar bond due to the lower electronegativity of sulfur.

### Step 3: Hydrogen Bonding
In \( H_2O \), the highly polar nature of the O-H bonds allows for strong hydrogen bonding between water molecules. These hydrogen bonds are strong intermolecular forces that hold the molecules together, resulting in a higher boiling point and making water a liquid at room temperature.

### Step 4: Van der Waals Forces in \( H_2S \)
In \( H_2S \), the intermolecular forces are primarily weak Van der Waals forces (or London dispersion forces). These forces are much weaker than hydrogen bonds, which means that \( H_2S \) molecules do not stick together as strongly as water molecules do, allowing \( H_2S \) to exist as a gas at room temperature.

### Step 5: Conclusion
The key difference lies in the strength of the intermolecular forces. The strong hydrogen bonding in \( H_2O \) keeps it in a liquid state, while the weak Van der Waals forces in \( H_2S \) allow it to exist as a gas.

### Final Answer
Thus, \( H_2O \) is a liquid and \( H_2S \) is a gas because oxygen forms stronger hydrogen bonds than sulfur, leading to stronger intermolecular forces in water.

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