Exploring Substances: Acidic, Basic, and Neutral – Very Short Answer Type Questions

Q1. What is an acid?

Ans. A substance that usually tastes sour and turns blue litmus paper red is called an acid.

Q2. Give two examples of natural acids found in food.

Ans. Citric acid in lemon and acetic acid in vinegar are natural acids found in food.

Q3. What is a base?

Ans. A substance that tastes bitter, feels soapy and turns red litmus paper blue is called a base.

Q4. Name any two common bases used at home.

Ans. Baking soda and soap solution are two common bases used at home.

Q5. What are neutral substances?

Ans. Substances which are neither acidic nor basic in nature are called neutral substances.

Q6. Give two examples of neutral substances.

Ans. Pure water and sugar solution are examples of neutral substances.

Q7. What is meant by "corrosive"?

Ans. Substances that can eat away or damage metals, skin or other materials are called corrosive.

Q8. Name one strong laboratory acid and one strong laboratory base.

Ans. Strong acid – Hydrochloric acid (HCl); strong base – Sodium hydroxide (NaOH).

Q9. What kind of taste is generally shown by acidic substances?

Ans. Acidic substances generally have a sour taste.

Q10. What kind of taste is generally shown by basic substances?

Ans. Basic substances usually have a bitter taste and feel soapy.

Q11. What is an indicator?

Ans. An indicator is a substance that shows a colour change in acidic and basic solutions.

Q12. Name any two natural indicators.

Ans. Litmus and turmeric are two natural indicators.

Q13. From where is litmus obtained?

Ans. Litmus is obtained from lichens.

Q14. What colour change is shown by blue litmus in an acid?

Ans. Blue litmus paper turns red in an acidic solution.

Q15. What colour change is shown by red litmus in a base?

Ans. Red litmus paper turns blue in a basic solution.

Q16. How does turmeric behave in the presence of a base?

Ans. Turmeric turns reddish-brown when a base is added to it.

Q17. What happens when turmeric paste is treated with lemon juice?

Ans. There is almost no colour change because lemon juice is acidic, not basic.

Q18. Name the plant whose petals are used to make china rose indicator.

Ans. Petals of the china rose (hibiscus) plant are used to make china rose indicator.

Q19. Why do we use indicators instead of tasting substances to check acidity or basicity?

Ans. Because many acids and bases are corrosive and tasting them can be harmful; indicators are safe.

Q20. How does a neutral solution affect litmus paper?

Ans. A neutral solution does not change the colour of either red or blue litmus paper.

Q21. What is neutralisation?

Ans. Neutralisation is the reaction in which an acid and a base react to form salt and water.

Q22. Name the products formed when an acid and a base neutralise each other.

Ans. Salt and water are formed during neutralisation.

Q23. Which type of substance is used to treat excess acidity in the stomach?

Ans. Basic substances called antacids are used to treat excess acidity.

Q24. Give one example of an antacid.

Ans. Milk of magnesia (magnesium hydroxide) is a commonly used antacid.

Q25. Why is lime added to acidic soil in fields?

Ans. Lime is basic and neutralises the excess acid in soil, making it fit for plant growth.

Q26. What is the nature of bee sting fluid – acidic or basic?

Ans. The fluid injected by a bee sting is acidic in nature.

Q27. Which household substance can be applied on a bee sting and why?

Ans. Baking soda solution can be applied because it is basic and neutralises the acid.

Q28. How can the effect of a wasp sting (which is basic) be reduced?

Ans. The effect can be reduced by applying a mild acid like vinegar or lemon juice.

Q29. What happens to the temperature of the mixture during neutralisation?

Ans. The temperature usually rises because neutralisation is often a heat-producing reaction.

Q30. Write a simple word equation for neutralisation.

Ans. Acid + Base → Salt + Water.

Q31. What is acid rain?

Ans. Rainwater that becomes more acidic due to dissolved acidic gases from air pollution is called acid rain.

Q32. Name two gases that cause acid rain.

Ans. Sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) cause acid rain.

Q33. How does acid rain affect plants?

Ans. Acid rain damages leaves, weakens roots and reduces plant growth.

Q34. How does acid rain affect aquatic life?

Ans. It makes water bodies too acidic, which can kill fish and other aquatic organisms.

Q35. Why are marble monuments damaged by acid rain?

Ans. Marble contains calcium carbonate, which reacts with acids in rain and slowly gets corroded.

Q36. What does pH tell us about a solution?

Ans. pH tells us how acidic or basic a solution is.

Q37. What is the pH of a neutral solution?

Ans. The pH of a neutral solution is 7.

Q38. If a solution has pH less than 7, what is its nature?

Ans. If pH is less than 7, the solution is acidic in nature.

Q39. If a solution has pH more than 7, what is its nature?

Ans. If pH is more than 7, the solution is basic in nature.

Q40. Why is it important for the pH of our blood to be almost constant?

Ans. Because many body processes work properly only in a narrow pH range; big changes can harm organs.

Q41. Name the acid present in our stomach.

Ans. Hydrochloric acid (HCl) is present in our stomach.

Q42. Why is hydrochloric acid present in the stomach?

Ans. It helps in digestion of food, especially proteins, and kills harmful germs.

Q43. Name one acid and one base used in car batteries and soap-making industries.

Ans. Acid – Sulphuric acid; Base – Sodium hydroxide.

Q44. Why is toothpaste usually basic in nature?

Ans. Toothpaste is basic to neutralise the acids produced by bacteria in the mouth.

Q45. How are bases useful in agriculture?

Ans. Bases like lime are used to neutralise acidic soil so that crops can grow better.

Q46. Why should we not taste any laboratory chemical?

Ans. Because laboratory chemicals may be poisonous or corrosive and can harm us.

Q47. What safety equipment should be worn while working with acids and bases?

Ans. We should wear safety goggles and, if needed, gloves or lab coats.

Q48. While diluting an acid, what should be added to what?

Ans. We should always add acid slowly to water, never water to acid.

Q49. What should you do if acid accidentally spills on your hand?

Ans. Wash the area with plenty of water and inform the teacher or adult immediately.

Q50. Why is it important to label acid and base bottles properly in the lab?

Ans. Proper labels prevent confusion and accidents by ensuring correct and safe use of chemicals.