Which of the following substances will change the colour of methyl orange indicator to yellow?
(i) Window cleaner (ii) Vinegar (iii) Apple juice (iv) Washing soda (v) Caustic soda (vi) Carbonic acid (vii) Citric acid

Options

A. (ii), (iv) and (vi) only
B. (i), (iv) and (v) only
C. (iii), (vi) and (vii) only
D. (i), (ii), (iv) and (v) only

Explanation

To determine which substances will change the color of methyl orange indicator to yellow, we first need to understand the behavior of methyl orange in different pH environments:

1. **Understanding Methyl Orange**: Methyl orange is a pH indicator that changes color based on the acidity or alkalinity of a solution. It appears red in acidic solutions (pH < 3.1) and turns yellow in neutral to alkaline solutions (pH > 4.4).

2. **Identifying the pH of Each Substance**:
- **Window Cleaner**: Typically contains ammonia or other alkaline substances, making it basic (pH > 7).
- **Vinegar**: Contains acetic acid, which is acidic (pH < 3).
- **Apple Juice**: Generally acidic due to natural fruit acids (pH < 4).
- **Washing Soda**: Sodium carbonate is a strong base (pH > 10).
- **Caustic Soda**: Sodium hydroxide is a strong base (pH > 13).
- **Carbonic Acid**: Formed when carbon dioxide dissolves in water, it is weakly acidic (pH < 5).
- **Citric Acid**: A weak acid found in citrus fruits (pH < 3).

3. **Determining Which Substances Will Change Methyl Orange to Yellow**:
- We are looking for substances that are basic (pH > 4.4).
- From our analysis:
- **Window Cleaner**: Basic → Will turn methyl orange yellow.
- **Washing Soda**: Basic → Will turn methyl orange yellow.
- **Caustic Soda**: Basic → Will turn methyl orange yellow.
- **Vinegar**: Acidic → Will not turn methyl orange yellow.
- **Apple Juice**: Acidic → Will not turn methyl orange yellow.
- **Carbonic Acid**: Weakly acidic → Will not turn methyl orange yellow.
- **Citric Acid**: Acidic → Will not turn methyl orange yellow.

4. **Final Answer**: The substances that will change the color of methyl orange indicator to yellow are:
- Window Cleaner
- Washing Soda
- Caustic Soda