$H_{2}S$ is more acidic than $H_{2}O$, because:

Question

Accepted Answer

Explanation:

1. **Justification for Option 3 (Correct Answer):**  
   The acidity of a compound is often related to the strength of the bond between hydrogen and the other atom in the molecule. In the case of $H_{2}S$ and $H_{2}O$, the bond strength plays a crucial role. The H-S bond in $H_{2}S$ is weaker than the H-O bond in $H_{2}O$. This weaker bond in $H_{2}S$ means that it is easier for the hydrogen ions (protons) to dissociate from the molecule, making $H_{2}S$ more acidic than $H_{2}O$. The weaker bond strength in $H_{2}S$ is due to the larger atomic size of sulfur compared to oxygen, which results in a longer and weaker bond with hydrogen.

2. **Explanation for why other options are incorrect:**

- **Option 1: Oxygen is more electronegative than sulphur.**  
     While it is true that oxygen is more electronegative than sulfur, this fact alone does not determine the acidity of the compounds. Electronegativity affects the polarity of the bond, but in this case, the bond strength is the more significant factor in determining acidity. The stronger H-O bond in $H_{2}O$ makes it less acidic compared to the weaker H-S bond in $H_{2}S$.

- **Option 2: Atomic number of sulphur is higher than oxygen.**  
     The atomic number of an element is not directly related to the acidity of its hydrides. While sulfur does have a higher atomic number than oxygen, this fact does not explain the difference in acidity. The key factor is the bond strength, not the atomic number.

- **Option 4: H-O bond is weaker as compared to H-S bond.**  
     This statement is incorrect. The H-O bond is actually stronger than the H-S bond. The stronger H-O bond in $H_{2}O$ means that it is less likely to release hydrogen ions, making it less acidic than $H_{2}S$. Therefore, this option does not correctly explain the observed acidity difference.

In conclusion, the correct explanation for why $H_{2}S$ is more acidic than $H_{2}O$ is due to the weaker H-S bond, as stated in Option 3.