Questions-Exploring Substances: Acidic, Basic, and Neutral

Important Question Answer: 

✨ 2-Marks Questions (Short Answer)

Q1. What is an indicator? Give one example.
✅ Answer:

• An indicator is a substance that shows whether another substance is acidic, basic, or neutral.

• Example: Litmus paper.

Q2. What is neutralisation?
✅ Answer:

• It is a chemical reaction between an acid and a base.

• It forms salt, water, and releases heat.

Q3. Name two substances that are acidic in nature.
✅ Answer:

• Lemon juice

• Vinegar

Q4. What happens when turmeric is mixed with soap solution?
✅ Answer:

• The yellow turmeric turns reddish-brown.

• It shows that soap is a base.

Q5. What is the colour of red litmus in acidic and basic solutions?
✅ Answer:

• In acid: Remains red

• In base: Turns blue

🌟 3-Marks Questions (Short Explanation)

Q1. Write any three natural indicators and their sources.
✅ Answer:

• Litmus – From lichens

• Turmeric – From turmeric root

• Red rose extract – From red rose petals

Q2. What happens when an ant bites? How can we reduce the pain?
✅ Answer:

• Ant injects formic acid into the skin.

• This causes pain and a burning feeling.

• Applying baking soda (a base) neutralises the acid and gives relief.

Q3. Write three uses of neutralisation in daily life.
✅ Answer:

• To treat ant bites using baking soda

• To treat acidic soil using lime

• To reduce the effect of acid in polluted lakes using bases

Q4. What are the properties of acids and bases? Give one example of each.
✅ Answer:

• Acids: Sour in taste, turn blue litmus red (e.g., lemon juice)

• Bases: Bitter and slippery, turn red litmus blue (e.g., soap solution)

Q5. What is the role of litmus paper in testing solutions?
✅ Answer:

• Blue litmus turns red in acids.

• Red litmus turns blue in bases.

• No colour change shows the solution is neutral.

💡 5-Marks Questions (Long Answer)

Q1. Explain the process of preparing and using red rose extract as an indicator.
✅ Answer:

• Collect and wash red rose petals.

• Crush petals and soak in hot water.

• Wait 5–10 minutes and filter the coloured water.

• Use this liquid to test substances.

• Turns red in acidic, green in basic, no change in neutral.

Q2. Describe how turmeric is used as an indicator.
✅ Answer:

• Make turmeric paste with water.

• Dip and dry filter paper in the paste to make turmeric paper.

• Put drops of different solutions on it.

• It turns reddish-brown in basic solutions.

• No colour change in acidic or neutral substances.

Q3. Write a short note on neutralisation with an example and its importance in daily life.
✅ Answer:

• Neutralisation = Acid + Base → Salt + Water + Heat

• Example: Lemon juice + Baking soda

• Importance:

  • Treating insect bites

  • Correcting acidic or basic soil

  • Treating acidic waste from factories before release

Q4. Compare the observations of litmus paper, turmeric, and red rose extract with different types of substances.
✅ Answer:

Q5. How do farmers and gardeners use neutralisation in soil treatment?
✅ Answer:

• Excess fertilizers can make soil acidic.

• Acidic soil harms plant growth.

• Farmers use lime (a base) to neutralise it.

• If soil is basic, organic matter is added to make it neutral.

• Healthy soil helps plants grow better.