Kit Library / Science / Chemistry
⚡ Topic Learning KitShared by a Veda teacher · Generated with Veda AI
Veda Bites are swipeable micro-lessons — each one teaches exactly one idea. The bites below come from this kit — swipe through them in the app.
💡 Key Idea
Every substance is one of these three.
Substances around us can be grouped into acids, bases, or neutral substances based on their chemical nature.
↳ Acids, bases and neutral substances differ in taste, feel and their effect on indicators.
📖 Definition
Indicators reveal a substance's true nature.
↳ Indicators change colour or smell to tell us the nature of a substance.
⭐ Important Fact
One paper, two colours, three answers.
↳ Litmus paper is the simplest way to identify acids, bases and neutral substances.
⚠️ Common Mistake
Tasting chemicals in a lab is dangerous.
↳ Use indicators, not your tongue, to identify acids and bases in the lab.
🌍 Real World
Your kitchen is a chemistry lab.
↳ Acids and bases are common in food, cleaning agents and medicines.
✏️ Example
Your kitchen spice is also an indicator.
↳ Turmeric changes colour only in bases, making it a useful natural indicator.
⚖️ Comparison
Sour vs bitter — know the difference.
↳ Acids and bases differ in taste, feel, litmus reaction and everyday examples.
❓ Did You Know
Litmus is made from living organisms.
Litmus is a natural dye extracted from lichen, a plant-like organism. It is the most commonly used natural indicator in school laboratories.
↳ Litmus, the classic indicator, is a natural dye obtained from lichen.
🛠️ Application
Some indicators work through your nose.
Olfactory indicators change their smell in acids and bases instead of their colour.
↳ Olfactory indicators detect acids and bases by a change in smell.
🎯 Exam Tip
One line saves you marks.
↳ Memorise the litmus colour rule — it is the most frequently asked point in exams.
🧠 Memory Trick
A quick trick to never mix it up.
Think "A-B-R": Acid → Blue litmus → Red. And "B-R-B": Base → Red litmus → Blue.
↳ Use the A-B-R and B-R-B pattern to recall litmus colour changes instantly.
A base soothes an acid sting.
An ant sting injects formic acid, causing pain. Rubbing baking soda (a base) on the skin neutralises the acid and gives relief.
↳ Bases like baking soda neutralise acid stings and reduce pain.
This topic explains how substances are classified as acids, bases or neutral based on their taste, feel, and effect on indicators like litmus. It covers natural and synthetic indicators, the meaning of neutral substances…
Full explanation, worked examples & memory tricks in the app
All 18 questions, laddered from warm-up to topper-level, each with its answer and the reasoning behind it.
Q1. Which ion is released by an acid when it dissolves in water?
BeginnerAnswers and explanations are in the Veda app.
Q2. A student dips blue litmus paper into a clear liquid and it turns red. What can the student conclude?
BeginnerAnswers and explanations are in the Veda app.
Q3. Which of the following substances is neutral?
BeginnerAnswers and explanations are in the Veda app.
Q4. What is the pH range of a basic substance?
BeginnerAnswers and explanations are in the Veda app.
Q5. Which natural indicator is extracted from lichens?
BeginnerAnswers and explanations are in the Veda app.
Q6. The pH scale is logarithmic: a change of 1 unit represents a ten-fold change in hydrogen ion concentration.
BeginnerAnswers and explanations are in the Veda app.
Q7. A substance has a pH of 3. Another has a pH of 5. How many times more acidic is the first substance?
IntermediateAnswers and explanations are in the Veda app.
Q8. Phenolphthalein is added to a solution and it turns pink. What does this indicate about the solution?
IntermediateAnswers and explanations are in the Veda app.
Q9. Hydrochloric acid reacts with sodium hydroxide. What are the products of this reaction?
IntermediateAnswers and explanations are in the Veda app.
Q10. Why does an antacid tablet relieve stomach acidity?
IntermediateAnswers and explanations are in the Veda app.
Q11. A farmer finds that the soil is too acidic for crops. Which substance should be added to raise the pH?
IntermediateAnswers and explanations are in the Veda app.
Q12. Which statement correctly describes the difference between a strong acid and a weak acid?
IntermediateAnswers and explanations are in the Veda app.
Q13. Turmeric stain on cloth turns reddish-brown when soap is applied. What does this show about soap?
IntermediateAnswers and explanations are in the Veda app.
Q14. Assertion (A): A neutral substance has a pH of exactly 7. Reason (R): A neutral substance releases neither $H^+$ nor $OH^-$ ions in a dominant way.
AdvancedAnswers and explanations are in the Veda app.
Q15. Consider these statements: I. Acids turn blue litmus red. II. Bases turn red litmus blue. III. Neutral substances turn blue litmus red. Which of the following is correct?
AdvancedAnswers and explanations are in the Veda app.
Q16. A solution of pH 2 is diluted until its pH becomes 4. Which explanation correctly describes what happened?
AdvancedAnswers and explanations are in the Veda app.
Q17. A farmer tests the pH of his soil and finds it to be 5.5. He wants to raise the pH to a neutral level. Which of the following substances should he apply to achieve this, and what reaction will occur?
AdvancedAnswers and explanations are in the Veda app.
Q18. A student is conducting an experiment to determine the pH of several household substances using red cabbage juice as an indicator. The student records the following observations: 1. Lemon juice turns the indicator pink. 2. Baking soda solution turns the indicator blue. 3. A salt solution shows no color change. Based on these observations, what can the student conclude about the pH of each substance?
AdvancedAnswers and explanations are in the Veda app.
26 flashcards in this kit — the app reviews them with spaced repetition so the right card returns on the right day.
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Word Match
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True False
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Memory Match
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Flashcard Battle
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Speed Quiz
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Guess Term
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Sequence Builder
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Categorization
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Revision Battle
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