Home › Science › Chapter 2 › Practice

Practice Sheet

Try first, then click "Show Answer" to check 👇

A. Multiple Choice (10)

1. Which of these is a natural indicator?
(a) Phenolphthalein(b) Methyl orange(c) Litmus(d) Bromothymol blue
Show Answer(c) Litmus — extracted from lichens.
2. Which acid is found in an ant sting?
(a) Citric acid(b) Formic acid(c) Lactic acid(d) Acetic acid
Show Answer(b) Formic acid — neutralised by moist baking soda.
3. A substance that turns turmeric paper red is:
(a) Acidic(b) Basic(c) Neutral(d) Salty
Show Answer(b) Basic — turmeric only reacts with bases.
4. The acid present in curd is:
(a) Tartaric acid(b) Citric acid(c) Lactic acid(d) Acetic acid
Show Answer(c) Lactic acid.
5. Which solution is neutral?
(a) Lemon juice(b) Soap solution(c) Sugar solution(d) Vinegar
Show Answer(c) Sugar solution — does not change litmus colour.
6. Which of these is an olfactory indicator?
(a) Litmus(b) Onion(c) Beetroot(d) Phenolphthalein
Show Answer(b) Onion — its smell changes in a base.
7. The product of a neutralisation reaction is:
(a) Acid + water(b) Base + salt(c) Salt + water + heat(d) Only water
Show Answer(c) Salt + water + heat.
8. Antacid is taken to neutralise:
(a) Soap in stomach(b) Excess HCl in stomach(c) Sugar(d) Bile
Show Answer(b) Excess HCl in stomach.
9. Red rose extract turns ______ in a basic solution.
(a) Red(b) Pink(c) Green(d) Yellow
Show Answer(c) Green.
10. To treat acidic soil, farmers add:
(a) Vinegar(b) Baking soda or lime(c) Salt(d) Sugar
Show Answer(b) Baking soda or lime — both are basic.

B. Fill in the Blanks (10)

1. Substances that are sour in taste are called ______.
Answeracidic / acids
2. Litmus is obtained from a plant called ______.
Answerlichen
3. Bases turn red litmus paper ______.
Answerblue
4. The acid present in lemon is ______ acid.
Answercitric
5. The acid present in vinegar is ______ acid.
Answeracetic
6. Indicators that change smell in acids/bases are called ______ indicators.
Answerolfactory
7. Acid + Base → Salt + Water + ______.
Answerheat
8. Phenolphthalein turns ______ in a basic solution.
Answerpink
9. Sugar solution and pure water are ______ in nature.
Answerneutral
10. ______ are taken to relieve acidity caused by excess HCl in the stomach.
AnswerAntacids

C. True or False (8)

  1. All bitter substances are bases.
    AnswerFalse — coffee and bitter gourd are bitter but not bases.
  2. Acids turn blue litmus red.
    AnswerTrue
  3. Turmeric is an indicator that detects only acids.
    AnswerFalse — it detects only bases.
  4. Neutralisation releases heat.
    AnswerTrue
  5. Lichens grow well in polluted areas.
    AnswerFalse — they grow in clean air.
  6. Calamine lotion is used to treat ant stings.
    AnswerTrue — it contains a base.
  7. Phenolphthalein is a natural indicator.
    AnswerFalse — it is synthetic (man-made).
  8. Pure water is neutral.
    AnswerTrue

D. Match the Following

Column AColumn B (your guess)
1. Citric acida. Curd
2. Acetic acidb. Lemon
3. Lactic acidc. Ant sting
4. Tartaric acidd. Vinegar
5. Formic acide. Tamarind
Show Answers1 → b (Lemon) · 2 → d (Vinegar) · 3 → a (Curd) · 4 → e (Tamarind) · 5 → c (Ant sting)

E. Short Answer (Write 2-3 lines)

1. Why should you never taste an unknown chemical?
Show Sample AnswerMany acids and bases are very strong and can burn the tongue, mouth or stomach. Some are even poisonous. We should always use safe indicators like litmus to find out their nature.
2. Why is toothpaste basic in nature?
Show Sample AnswerBacteria in our mouth break down food and produce acids that damage tooth enamel. Toothpaste is basic — it neutralises this acid and protects teeth from decay.
3. Define an indicator. Give two examples.
Show Sample AnswerAn indicator is a substance that changes its colour (or smell) when it comes in contact with an acid or a base. Examples: litmus and turmeric.
4. What is neutralisation? Write its general equation.
Show Sample AnswerNeutralisation is the reaction between an acid and a base in which they cancel each other's effect to form salt and water, with heat released.
Acid + Base → Salt + Water + Heat
5. How does a hydrangea plant act as a natural indicator?
Show Sample AnswerThe flowers of a hydrangea plant change colour with the soil — they appear blue in acidic soil and pink in basic soil. So they tell us about the soil's nature naturally.
🎯 Goal: Score 80%+ on practice before attempting the school test. If you get any wrong, re-read that section in Explanation and try again.
← Q & A Quick Revision →