pH scale (0–14)
Acidic < 7, neutral = 7, basic > 7 — with everyday examples.
Step 1 — Study the figure
Cover the label key on the image, name each numbered part, then check the explanations below.
Step 2 — Diagram details for students
What this diagram shows
The pH scale from 0 to 14 measures how acidic or basic a solution is. Lower than 7 means acidic, 7 means neutral, and higher than 7 means basic. Class 10 answers should link pH numbers to H⁺ / OH⁻ idea and everyday examples.
Numbered parts — mark & remember
Match each number on the figure with the meaning below. Say the function aloud once.
1 Acidic (< 7)
Acidic solutions have higher hydrogen ion concentration, so pH is less than 7. Lemon juice, vinegar, and dilute HCl are common acidic examples. Stronger acids have lower pH values on this scale.
2 Neutral (= 7)
A neutral solution has pH 7 under standard Class 10 teaching (pure water at about 25 °C). Here H⁺ and OH⁻ concentrations are balanced. Distilled water is the usual exam example of neutrality.
3 Basic (> 7)
Basic or alkaline solutions have higher OH⁻ concentration, so pH is greater than 7. Soap solution, milk of magnesia, and sodium hydroxide solution are typical basics. Higher pH means more strongly basic character.
4 Indicator colours
Universal indicator or pH paper gives a colour that you match to a chart to read pH. Always state both the colour and the pH range in practical answers. Indicators do not change the identity of acid or base; they only report strength roughly.
How to read this figure
- Move left for more acidic and right for more basic on the usual horizontal scale.
- Memorise at least one example for acid, neutral, and base.
- Dilution moves extreme acids/bases toward 7 but does not make them “become each other”.
Redraw for board marks
- Draw a horizontal bar marked 0 to 14.
- Mark 7 clearly as neutral in the middle.
- Shade acid and base sides differently and add 2–3 examples.
Board answer tip: Define pH regions, give one example for each, and mention how universal indicator helps measure pH.
Exam tips — don’t lose marks
- Tooth decay links to acidic pH in the mouth after sugary food.
- Stomach has strongly acidic pH needed for pepsin action.
- Never write that pH of water is always exactly 7 in every real sample — use the NCERT ideal statement carefully.