NCERT Class 10 Science Chapter: "Acids, Bases and Salts" intext and end exercise questions along with their question numbers and full questions, as per your request (latest NCERT 2024–25 pattern):
Intext Questions (with question numbers and full text):
Q1. You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
Q2. Why should curd and sour substances not be kept in brass and copper vessels?
Q3. Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?
Q4. Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.
Q5. Why do HCl, HNO₃, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?
Q6. Why does an aqueous solution of an acid conduct electricity?
Q7. Why does dry HCl gas not change the colour of the dry litmus paper?
Q8. While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?
Q9. How is the concentration of hydronium ions (H₃O⁺) affected when a solution of an acid is diluted?
Q10. How is the concentration of hydroxide ions (OH⁻) affected when excess base is dissolved in a solution of sodium hydroxide?
Q11. You have two solutions, A and B. The pH of solution A is 6 and pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of this is acidic and which one is basic?
Q12. What effect does the concentration of H⁺ (aq) ions have on the nature of the solution?
Q13. Do basic solutions also have H⁺ (aq) ions? If yes, then why are these basic?
Q14. Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate)?
Q15. What is the common name of the compound CaOCl₂?
Q16. Name the substance which on treatment with chlorine yields bleaching powder.
Q17. Name the sodium compound which is used for softening hard water.
Q18. What will happen if a solution of sodium hydrogen carbonate is heated? Give the equation of the reaction involved.
Q19. Write an equation to show the reaction between Plaster of Paris and water.
End Exercise Questions:
Q1. A solution turns red litmus blue, its pH is likely to be
(a) 1
(b) 4
(c) 5
(d) 10
Q2. A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains
(a) NaCl
(b) HCl
(c) LiCl
(d) KCl
Q3. 10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount of HCl solution required to neutralise it will be
(a) 4 mL
(b) 8 mL
(c) 12 mL
(d) 16 mL
Q4. Which one of the following types of medicines is used for treating indigestion?
(a) Antibiotic
(b) Analgesic
(c) Antacid
(d) Antiseptic
Q5. Write word equations and then balanced equations for the reactions taking place when —
(a) Dilute sulphuric acid reacts with zinc granules.
(b) Dilute hydrochloric acid reacts with magnesium ribbon.
(c) Dilute sulphuric acid reacts with aluminium powder.
(d) Dilute hydrochloric acid reacts with iron filings.
Q6. Compounds such as alcohol and glucose also contain hydrogen but are not categorised as acids. Describe an activity to prove it.
Q7. Why does distilled water not conduct electricity, whereas rainwater does?
Q8. Why do acids not show acidic behaviour in the absence of water?
Q9. Five solutions A, B, C, D, and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9, respectively.
(a) Which solution is neutral?
(b) Which solution is strongly alkaline?
(c) Which solution is strongly acidic?
(d) Which solution is weakly acidic?
(e) Which solution is weakly alkaline?
Q10. Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH₃COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why?
Q11. Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.
Q12. A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?
Q13. Plaster of Paris should be stored in a moisture-proof container. Explain why?
Q14. What is a neutralisation reaction? Give two examples.
Q15. Give two important uses of washing soda and baking soda.
Class 10 Science – Chapter: Acids, Bases and Salts (NCERT)
Intext + End Exercise Questions with Answers in English, as per the latest NCERT syllabus (2024–25):
🔹 Intext Questions with Answers
Q1. You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
Answer:
Dip red litmus paper into each test tube:
-
In acid → remains red
-
In base → turns blue
-
In water → remains red (neutral, but no effect on red litmus)
Q2. Why should curd and sour substances not be kept in brass and copper vessels?
Answer:
Because curd and sour substances contain acids that react with brass or copper, forming harmful compounds (salts of copper) which may be poisonous.
Q3. Which gas is usually liberated when an acid reacts with a metal? How will you test for the presence of this gas?
Answer:
Hydrogen gas is liberated. Bring a burning matchstick near the gas — it burns with a ‘pop’ sound.
Q4. Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation.
Answer:
The gas is CO₂. Metal compound A is calcium carbonate.
Equation:
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
Q5. Why do HCl, HNO₃ show acidic character in aqueous solution while glucose and alcohol do not?
Answer:
HCl and HNO₃ ionise in water to give H⁺ ions. Glucose and alcohol do not produce H⁺ ions in water, hence not acidic.
Q6. Why does an aqueous solution of an acid conduct electricity?
Answer:
Due to the presence of ions (H⁺), which carry current.
Q7. Why does dry HCl gas not change the colour of dry litmus paper?
Answer:
Because dry HCl gas does not ionise without water, so no H⁺ ions are released.
Q8. Why is acid added to water and not water to acid?
Answer:
Adding water to acid causes a lot of heat and may splash acid. Adding acid to water is safer, as heat is absorbed more easily by water.
Q9. How is the concentration of H₃O⁺ ions affected when an acid is diluted?
Answer:
The concentration of H₃O⁺ ions decreases.
Q10. How is the concentration of OH⁻ ions affected when excess base is dissolved in sodium hydroxide solution?
Answer:
The concentration of OH⁻ ions increases.
Q11. Solutions A (pH 6) and B (pH 8). Which is more acidic?
Answer:
Solution A is acidic (more H⁺ ions), and Solution B is basic.
Q12. What effect does the concentration of H⁺ ions have on nature of solution?
Answer:
More H⁺ ions → more acidic the solution.
Q13. Do basic solutions have H⁺ ions? If yes, why are they basic?
Answer:
Yes, but they have more OH⁻ ions than H⁺ ions, so they are basic.
Q14. Under what soil condition is lime added by farmers?
Answer:
When soil is acidic, lime (a base) is added to neutralise it.
Q15. What is the common name of CaOCl₂?
Answer:
Bleaching powder.
Q16. Name the substance which on treatment with chlorine yields bleaching powder.
Answer:
Slaked lime (Ca(OH)₂)
Q17. Name the sodium compound used for softening hard water.
Answer:
Washing soda (Na₂CO₃)
Q18. What happens when sodium hydrogen carbonate is heated?
Answer:
It decomposes into sodium carbonate, CO₂ and water.
Equation:
2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O
Q19. Write the reaction between Plaster of Paris and water.
Answer:
CaSO₄·½H₂O + 1½H₂O → CaSO₄·2H₂O
🔹 End Exercise Questions with Answers
Q1. A solution turns red litmus blue. Its pH is likely to be –
Answer: (d) 10
Q2. A solution reacts with crushed egg-shells to give CO₂. The solution is –
Answer: (b) HCl
Q3. 10 mL NaOH is neutralised by 8 mL HCl. So, 20 mL NaOH needs –
Answer: (d) 16 mL
Q4. Medicine used for treating indigestion –
Answer: (c) Antacid
Q5. Word + balanced equations:
(a) Zinc + Sulphuric acid → Zinc sulphate + Hydrogen
Zn + H₂SO₄ → ZnSO₄ + H₂
(b) Magnesium + HCl → Magnesium chloride + H₂
Mg + 2HCl → MgCl₂ + H₂
(c) Aluminium + Sulphuric acid → Aluminium sulphate + H₂
2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂
(d) Iron + HCl → Iron chloride + H₂
Fe + 2HCl → FeCl₂ + H₂
Q6. Alcohol and glucose contain hydrogen but are not acids. Activity?
Answer:
Use a conductivity tester. Glucose/alcohol solution do not conduct electricity → no free H⁺ ions → not acidic.
Q7. Why does distilled water not conduct electricity, but rainwater does?
Answer:
Distilled water lacks ions. Rainwater contains dissolved CO₂ forming carbonic acid → ions → conducts electricity.
Q8. Why do acids not show acidic behaviour in absence of water?
Answer:
Acids need water to ionise and release H⁺ ions.
Q9. Five solutions with pH 1, 4, 7, 9, 11:
(a) Neutral → 7 (D)
(b) Strongly alkaline → 11 (C)
(c) Strongly acidic → 1 (B)
(d) Weakly acidic → 4 (A)
(e) Weakly alkaline → 9 (E)
Q10. Fizzing with HCl and CH₃COOH?
Answer:
HCl gives more fizz as it is a strong acid and reacts faster with magnesium.
Q11. pH of milk turns from 6 to...?
Answer:
As it turns to curd, it becomes more acidic → pH decreases.
Q12.
(a) Baking soda makes milk alkaline to prevent curdling.
(b) Curd formation takes longer in alkaline conditions.
Q13. Why Plaster of Paris is kept in moisture-proof container?
Answer:
To prevent it from absorbing water and hardening into gypsum.
Q14. What is neutralisation reaction? Examples?
Answer:
Reaction between acid and base to form salt + water.
Examples:
-
HCl + NaOH → NaCl + H₂O
-
H₂SO₄ + Ca(OH)₂ → CaSO₄ + 2H₂O
Q15. Two uses of:
Washing Soda (Na₂CO₃):
-
Softening hard water
-
Cleaning agent
Baking Soda (NaHCO₃):
-
In baking (releases CO₂)
-
Used in fire extinguishers
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