Methyl orange is a pH indicator frequently used in titration because of its clear and distinct colour variance at different pH values. Methyl orange shows pink colour in acidic medium and yellow colour in basic medium. Because it changes colour at the pH of a mid strength acid, it is usually used in titration for acids. Unlike a universal indicator, methyl orange does not have a full spectrum of colour change, but it has a sharp end point.

Explanation:

Introduction:
Methyl orange is a pH indicator that is commonly used in chemistry labs to determine the acidity or alkalinity of a solution. It is an azo compound that changes color depending on the pH of the solution it is in.

Acids and Bases:
Acids are substances that release hydrogen ions (H+) when dissolved in water, while bases are substances that release hydroxide ions (OH-) when dissolved in water. The concentration of hydrogen ions in a solution determines its acidity or alkalinity, which is measured on a scale called the pH scale.

Methyl Orange as a pH Indicator:
Methyl orange is a pH indicator that changes color depending on the pH of the solution. It is commonly used to determine whether a solution is acidic or basic.

Color Changes of Methyl Orange:
Methyl orange has a characteristic color range depending on the pH of the solution:

1. Acidic Solutions: In acidic solutions, which have a low pH, methyl orange appears pink or red.

2. Neutral Solutions: In neutral solutions, which have a pH of around 7, methyl orange appears orange or yellow. This is the color that gives the compound its name.

3. Basic Solutions: In basic solutions, which have a high pH, methyl orange appears yellow or orange.

Reason for the Color Change:
The color change of methyl orange is due to the different forms of the compound that are present at different pH values. In acidic solutions, methyl orange is present in its protonated form, which is pink or red in color. In basic solutions, it is present in its deprotonated form, which is yellow or orange in color.

Why option 'B' is the correct answer:
Acids are substances that release hydrogen ions (H+) when dissolved in water, which lowers the pH of the solution. As a result, methyl orange will change color and appear pink or red in the presence of acids. Therefore, the correct answer is option 'B' - Pink/Red.

B pink and red