Consider the following statements:
(a) Both acids and bases change colour of all indicators.
(b) If an indicator gives a colour change with an acid, it does not give a change with a base.
(c) If an indicator changes colour with a base, it does not change colour with an acid.
(d) Change of colour in an acid and a base depends on the type of the indicator.
Which of these statements are correct?

Options

A. All four
B. a and d
C. b and c
D. only d

Answer

To solve the question, we need to analyze each statement regarding acids, bases, and indicators. Let's break down the statements one by one:

### Step 1: Analyze Statement (a)
**Statement (a)**: Both acids and bases change the color of all indicators.

- This statement is **false**. Not all indicators change color in both acidic and basic environments. For example, red litmus paper does not change color in an acidic solution, while it turns blue in a basic solution. Conversely, blue litmus paper turns red in an acidic solution but does not change in a basic solution.

### Step 2: Analyze Statement (b)
**Statement (b)**: If an indicator gives a color change with an acid, it does not give a change with a base.

- This statement is **true**. For instance, if blue litmus paper changes color in an acidic solution (turning red), it does not change color when placed in a basic solution.

### Step 3: Analyze Statement (c)
**Statement (c)**: If an indicator changes color with a base, it does not change color with an acid.

- This statement is also **true**. For example, if red litmus paper changes color in a basic solution (turning blue), it does not change color when placed in an acidic solution.

### Step 4: Analyze Statement (d)
**Statement (d)**: Change of color in an acid and a base depends on the type of the indicator.

- This statement is **true**. Different indicators react differently to acids and bases. For example, turmeric changes to yellow in acidic solutions and red in basic solutions, while litmus paper has its own distinct color changes.

### Conclusion
Now, let's summarize the correctness of each statement:
- **Statement (a)**: False
- **Statement (b)**: True
- **Statement (c)**: True
- **Statement (d)**: True

### Final Answer
The correct statements are B, C, and D. Therefore, the correct option is **Option 3** (B and C).

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