Which of the following statements is correct about an aqueous solution of an acid and of a base ?
(i) Higher the pH, stronger the acid
(ii) Higher the pH, weaker the acid
(iii) lower the pH, stronger the base
(iv) Lower the pH, weaker the base

Options

A. (i) and (iii)
B. (ii) and (iii)
C. (i) and (iv)
D. (ii) and (iv)

Explanation

To solve the question, we need to analyze the statements given about the pH of aqueous solutions of acids and bases. Let's break it down step by step.

### Step 1: Understand the pH Scale
The pH scale ranges from 0 to 14:
- A pH of 7 is considered neutral (pure water).
- A pH less than 7 indicates an acidic solution.
- A pH greater than 7 indicates a basic (alkaline) solution.

**Hint:** Remember that the pH scale helps us determine whether a solution is acidic, neutral, or basic.

### Step 2: Analyze Each Statement
Now, let's evaluate each statement one by one:

**Statement (i): Higher the pH, stronger the acid.**
- This statement is incorrect. A higher pH indicates a weaker acid or a stronger base.

**Hint:** Recall that stronger acids have lower pH values.

**Statement (ii): Higher the pH, weaker the acid.**
- This statement is correct. As the pH increases, the acidity decreases, meaning the acid is weaker.

**Hint:** A higher pH means less hydrogen ion concentration, which corresponds to a weaker acid.

**Statement (iii): Lower the pH, stronger the base.**
- This statement is incorrect. A lower pH indicates a stronger acid, not a base.

**Hint:** Stronger bases correspond to higher pH values.

**Statement (iv): Lower the pH, weaker the base.**
- This statement is correct. A lower pH means the solution is more acidic, which indicates that the base is weaker.

**Hint:** A lower pH means more hydrogen ions, which reduces the basicity.

### Step 3: Conclusion
From the analysis:
- The correct statements are (ii) and (iv).
- Therefore, the correct answer to the question is that the statements (ii) and (iv) are correct.

**Final Answer:** The correct statements are (ii) Higher the pH, weaker the acid and (iv) Lower the pH, weaker the base.