Chapter 2: Exploring Substances Acidic Basic…

✓ Free notes Class 7 Science 1 study file

About these notes

Class 7 Science Chapter 2 Exploring Substances Acidic Basic and Neutral (CBSE/Bihar Board) notes give clear definitions, pH ideas, indicator tests and practical examples for quick revision. Main sub-topics: pH scale and pH values, common indicators (litmus, methyl orange, phenolphthalein), properties of acids and bases, neutralisation (acid + base → salt + water), reactions with metals and carbonates, common examples (HCl, H2SO4, NaOH) and safety tips. Suitable for Class 7 CBSE and Bihar Board students preparing for school tests, chapter test practice and MCQ-based mock tests on Merit Spring ROH.

Key points you will learn

pH scale: acidic (pH7)
Acids produce H+ ions in water; bases produce OH- ions
Common indicators and colour changes: litmus, methyl orange, phenolphthalein
Neutralisation reaction: acid + base → salt + H2O
Reaction of acids with metals produces H2; with carbonates produces CO2
Examples of common substances: HCl, H2SO4, NaOH and their typical uses
Safety tip: handle acids and bases with care, use goggles and avoid direct contact

What is inside this chapter

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Exploring Substances Acidic Basic and Neutral - Chapter 2 Notes (Class 7 Science)

Class 7 Science Exploring Substances Acidic Basic and Neutral - Chapter 2 handwritten-style revision notes for CBSE and Bihar Board students.

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Questions students ask

Where to find Class 7 Science Chapter 2 notes and important questions?

The chapter notes are on the Merit Spring ROH page for Chapter 2; for important questions and MCQ practice use the site’s chapter test and mock tests sections to revise and check answers.

What is an acid and a base?

An acid is a substance that produces H+ ions in water and usually tastes sour, while a base produces OH- ions and feels soapy; acids turn blue litmus red and bases turn red litmus blue. Examples: HCl (acid), NaOH (base).

Difference between acid and base in short?

Acids donate H+ ions and have pH less than 7; bases donate OH- ions and have pH greater than 7. Acids react with metals and carbonates; bases are slippery and neutralise acids to form salts and water.

How do indicators and pH paper test substances?

Indicators change colour in acidic or basic solutions: blue/red litmus, methyl orange, phenolphthalein; pH paper gives an approximate numeric pH. Use indicators to classify substances as acidic, basic or neutral.

How can I remember pH values for common items?

Remember the rule: pH7 basic; link examples—lemon juice (acidic), pure water (7), soap solution (basic)—and practise with quick MCQ drills for faster recall.

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