Consider the following molecules :
`H_(2)O ,H_(2)S ,H_(2) Se ,H_(2)Te`
Arrange these molecules in increasing order of acidity

Answer

To arrange the molecules \( H_2O, H_2S, H_2Se, \) and \( H_2Te \) in increasing order of acidity, we can follow these steps:

### Step 1: Understand the Concept of Acidity
Acidity refers to the ability of a molecule to donate a proton (H\(^+\)). The more easily a molecule can lose a proton, the stronger the acid it is.

### Step 2: Identify the Group and Trend
All the given molecules belong to the same group in the periodic table (Group 16, the chalcogens). As we move down the group from oxygen to tellurium, the size of the atoms increases.

### Step 3: Analyze the Bond Strength
As we move down the group:
- The bond strength between hydrogen and the chalcogen atom decreases due to the increase in atomic size.
- This means that the H-X bond (where X is O, S, Se, or Te) becomes weaker as we go from \( H_2O \) to \( H_2Te \).

### Step 4: Compare Acidity
- \( H_2O \) has the strongest bond and is the least acidic.
- \( H_2S \) is more acidic than \( H_2O \) because the H-S bond is weaker than the H-O bond.
- \( H_2Se \) is more acidic than \( H_2S \) for the same reason, as the H-Se bond is weaker than the H-S bond.
- \( H_2Te \) is the most acidic because the H-Te bond is the weakest among them.

### Step 5: Arrange in Increasing Order of Acidity
Based on the bond strengths and the ability to donate protons, we can arrange the molecules in increasing order of acidity as follows:
\[ H_2O < H_2S < H_2Se < H_2Te \]

### Final Answer
The increasing order of acidity is:
\[ H_2O < H_2S < H_2Se < H_2Te \]

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