Class 7ScienceAcids, Bases and Salts

pH Scale and Indicators

pH measures acidity/alkalinity: 0-14 scale. pH < 7: acid. pH = 7: neutral (pure water). pH > 7: base/alkali. Litmus: natural indicator from lichens. Turns RED in acid, BLUE in base. Turmeric: yellow in acid/neutral, RED-BROWN in base. Phenolphthalein: colorless in acid, pink in base. Methylorange: red in acid, yellow in base.

How to study this topic

Read the core explanation once without solving.
Open the formula links below and connect them with the topic meaning.
Practice the 10 example pages one by one.
Use the AI ask page for text, voice or image-based doubts.

10 example pages

Concept check 1

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on concept check and show the working clearly.

Definition to application 2

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on definition to application and show the working clearly.

Formula warm-up 3

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on formula warm-up and show the working clearly.

Reasoning practice 4

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on reasoning practice and show the working clearly.

Board-style short answer 5

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on board-style short answer and show the working clearly.

Mistake correction 6

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on mistake correction and show the working clearly.

Visual interpretation 7

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on visual interpretation and show the working clearly.

Applied word problem 8

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on applied word problem and show the working clearly.

Revision challenge 9

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on revision challenge and show the working clearly.

Exam recap 10

For Class 7 Science, explain or solve a ph scale and indicators question from the chapter "Acids, Bases and Salts". Focus on exam recap and show the working clearly.