NCERT Solutions Class 10 Science Chapter 2: Acid, Bases and Salts

So, have you ever wondered why a substance tastes sour or, for that matter, bitter? The answers to these questions lie in the very fascinating realms of acids, bases, and salts. You will venture through an engaging journey in discovering these basic chemical compounds along with their properties as per the detailed solutions while studying Chapter 2 NCERT Solutions Class 10 Science.

1.0Download Class 10 Science Chapter 2 NCERT Solutions PDF Online

Students can download NCERT Solutions Class 10 Science Chapter 2 (Acid, base and salts) from the below table in PDF format. 

2.0Topics Covered in Class 10 Science Chapter 2: Acids, Bases, and Salts

1. Chemical Properties of Acids, Bases, and Salts

• Acids and bases in the laboratory
• How do acids and bases react with metals?
• Reactions of metal carbonates and metal hydrogen carbonates
• Reaction of metallic oxides with acids
• Reaction of non-metallic oxides with bases

2. What Do All Acids and Bases Have in Common?

• Acids and bases in water solutions

3. How Strong Are Acids and Base Solutions?

• Importance of pH

4. More About Salts

• Family of salts
• pH of salts
• Chemicals from common salts
• Crystals of salts

3.0Acid, Bases and Salts

Acids, bases, and salts are fundamental in chemistry with a wide range of applications. Acids release hydrogen ions, bases release hydroxide ions, and salts are the products of their reactions. The pH scale helps categorize substances based on their acidic or basic nature.

Acids:

• Acids are substances that release hydrogen ions (H⁺) when dissolved in water.
• They have a sour taste (e.g., citric acid in lemons).
• Acids turn blue litmus paper red.
• They are classified into:
• Strong acids (e.g., hydrochloric acid, sulfuric acid) which dissociate completely in water.
• Weak acids (e.g., acetic acid, citric acid) which partially dissociate in water.
• Properties of acids:
• They corrode metals (e.g., HCl reacts with zinc to release hydrogen gas).
• React with bases to form salt and water (neutralization reaction).

Bases:

• Bases are substances that release hydroxide ions (OH⁻) when dissolved in water.
• They have a bitter taste and feel slippery (e.g., soap).
• Bases turn red litmus paper blue.
• Types of bases:
• Strong bases (e.g., sodium hydroxide, potassium hydroxide) dissociate completely in water.
• Weak bases (e.g., ammonia, aluminum hydroxide) partially dissociate.
• Properties of bases:
• They can neutralize acids to form salts and water.
• Alkalis are bases that dissolve in water (e.g., NaOH, KOH).

Salts:

• Salts are compounds formed when an acid reacts with a base, resulting in the neutralization of the acid.
• Example: HCl + NaOH → NaCl + H₂O (hydrochloric acid + sodium hydroxide → sodium chloride + water).
• Salts can be categorized as:
• Neutral salts (e.g., sodium chloride, NaCl)
• Acidic salts (e.g., ammonium chloride, NH₄Cl), which come from a weak base and a strong acid.
• Basic salts (e.g., sodium carbonate, Na₂CO₃), which come from a strong base and a weak acid.

pH Scale:

• The pH scale measures the acidity or alkalinity of a solution.
• It ranges from 0 to 14:
• pH < 7: Acidic (e.g., lemon juice, vinegar).
• pH = 7: Neutral (e.g., water).
• pH > 7: Alkaline (e.g., baking soda, soap).
• pH is calculated by the concentration of H⁺ ions in a solution: pH = -log[H⁺].

Indicators:

• Indicators are substances that change color depending on the pH of the solution.
• Litmus paper (blue for base, red for acid).
• Phenolphthalein (colorless in acidic, pink in alkaline solutions).
• Methyl orange (red in acid, yellow in base).

Neutralization Reactions:

• A neutralization reaction occurs when an acid and a base combine to form water and salt.
• Example: HCl + NaOH → NaCl + H₂O.

4.0Importance of Acids, Bases, and Salts

• Acids are used in manufacturing fertilizers, cleaning agents, and in food preservation.
• Bases are used in soaps, cleaning products, and in neutralizing acids.
• Salts have various uses in food preservation, as fertilizers, and in the chemical industry.

5.0What Will Students Learn in Chapter : Acids, Bases, and Salts 

1. Acid-Base Theories – Arrhenius, Brønsted-Lowry, and Lewis concepts explaining acid-base behavior.
2. pH, Strength & Ionization – pH scale, Ka, Kb, pKa, pKb, degree of ionization, and Ostwald’s dilution law.
3. Buffer Solutions & Salt Hydrolysis – Buffer action, Henderson-Hasselbalch equation, and pH of salt solutions.
4. Acid-Base Titrations & Indicators – Titration curves, equivalence points, and indicator selection.
5. Applications & Common Ion Effect – Neutralization in industry, acid rain, pH control, and solubility effects.

6.0Sample NCERT Solutions for Class 10 Science Chapter 2 Acid, Bases and Salts

1. 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?

Ans. (i) Put the red litmus paper in all the test tubes, turn by turn. The solution which turns red litmus to blue will be a basic solution. The blue litmus paper formed here can now be used to test the acidic solution.

(ii) Put the blue litmus paper obtained above in the remaining two test tubes, turn by turn. The solution which turns the blue litmus paper to red will be the acidic solution.

(iii) The solution which has no effect on any litmus paper will be neutral and hence it will be distilled water.

2. Why should curd and sour substances not be kept in brass and copper vessels?

Ans. Curd and other sour substances contain acids. Therefore, when they are kept in brass and copper vessels, the metal reacts with the acid to liberate hydrogen gas and harmful products, thereby spoiling the food.

3. 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?

Ans. Hydrogen gas is usually liberated when an acid reacts with a metal.

For example,

Step 1 - Take few pieces of zinc granules and add 5 mL of dilute H₂SO₄.

Step 2 - Shake it and pass the gas produced into a soap solution. The bubbles are formed in the soap solution. These soap bubbles contain hydrogen gas.

Test for hydrogen gas: The evolved hydrogen gas can be tested by bringing a burning candle near the soap bubbles. Hydrogen gas burns with a pop sound. (Refer Active Chemistry 3).

4. 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.

Ans. CaCO₃(s) + 2HCl(aq) → CaCl₂(s) + CO₂(g) + H₂O(l)

5. Why do HCl, HNO3, etc., show acidic character in aqueous solution while solutions of compounds like alcohol and glucose do not show acidic character?

Ans. HCl and HNO3 dissociate in the presence of water to form hydrogen or hydronium ions.

Although aqueous solutions of glucose and alcohol contain hydrogen, these cannot dissociate in water to form hydrogen or hydronium ions. Hence, they do not show acidic character.

6. Why does an aqueous solution of an acid conduct electricity?

Ans. Acids dissociate in aqueous solutions to form ions. These ions are responsible for conduction of electricity.

7. Why does dry HCl gas not change the colour of the dry litmus paper?

Ans. Acids do not ionize in the absence of water to liberate H₃O+ which shows acidic nature of a solution. Therefore, dry HCl gas does not change the colour of the dry litmus paper because it does not contain H+ ions.

8. While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

Ans. It is recommended that the acid should be added to water and not water to the acid because the process of dissolving an acid in water is exothermic. If water is added to acid, since a large amount of acid is present, a large amount of heat is generated. Therefore, the mixture splashes out and causes burns.

9. How is the concentration of hydronium ions (H₃O+) affected when a solution of an acid is diluted?

Ans. When an acid is diluted, the concentration of hydronium ions (H₃O+) per unit volume decreases. This means that the strength of the acid decreases.

10. How is the concentration of hydroxide ions (OH−) affected when excess base is dissolved in a solution of sodium hydroxide?

Ans. The concentration of hydroxide ions (OH−) would increase when excess base is dissolved in a solution of sodium hydroxide.

11. 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?

Ans. A pH value of less than 7 indicates an acidic solution, while greater than 7 indicates a basic solution. Therefore, the solution with pH=6 is acidic and has more hydrogen ion concentration than the solution of pH=8 which is basic.

12. What effect does the concentration of H+(aq) ions have on the nature of the solution?

Ans. If the concentration of H+ ions is increased, the solution becomes more acidic. If the concentration of H+ ions is decreased, the solution becomes less acidic or more basic.

13. Do basic solutions also have H+(aq) ions? If yes, then why are these basic?

Ans. Yes, a basic solution also has H+(aq) ions. However, their concentration is less as compared to the concentration of OH−(aq) ions which makes the solution basic.

14. 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)?

Ans. If the soil is acidic and improper for cultivation, then to neutralise the acidity of the soil, the farmer would treat the soil with quick lime or slaked lime or chalk.

15. What is the common name of the compound CaOCl₂?

Ans. The common name of the compound CaOCl₂ is bleaching powder.

16. Name the substance which on treatment with chlorine yields bleaching powder?

Ans. Calcium hydroxide [Ca(OH)₂], on treatment with chlorine, yields bleaching powder.

17. Name the sodium compound which is used for softening hard water.

Ans. Washing soda (Na₂CO₃ .10H₂O) is used for softening hard water.

18. What will happen if a solution of sodium hydrogen carbonate is heated? Give the equation of the reaction involved.

Ans. When a solution of sodium hydrogen carbonate is heated, sodium carbonate and water are formed with the evolution of carbon dioxide gas.

2NaHCO₃ (heated) → Na₂CO₃ + H₂O + CO₂ ↑

Sodium Hydrogen Carbonate → Sodium Carbonate + Water + Carbon Dioxide

19. Write an equation to show the reaction between Plaster of Paris and water.

Ans. The chemical equation for the reaction of Plaster of Paris and water can be represented as-

CaSO₄ · 1/2 H2O + 1 1/2 H₂O → CaSO₄ · 2H₂O

Plaster of Paris + Water → Gypsum

20. A solution turns red litmus blue, its pH is likely to be

(1) 1

(2) 4

(3) 5

(4) 10

Ans. (4) 10

21. A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains

(1) NaCl

(2) HCl

(3) LiCl

(4) KCl

Ans. (2) HCl

22. 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 (the same solution as before) required to neutralise it will be

(1) 4 mL

(2) 8 mL

(3) 12 mL

(4) 16 mL

Ans. (4) 16 mL

23. Which one of the following types of medicines is used for treating indigestion?

(1) Antibiotic

(2) Analgesic

(3) Antacid

(4) Antiseptic

Ans. (3) Antacid

24. Write word equations and then balanced equations for the reaction taking place when -

(1) Dilute sulphuric acid reacts with zinc granules.

(2) Dilute hydrochloric acid reacts with magnesium ribbon.

(3) Dilute sulphuric acid reacts with aluminium powder.

(4) Dilute hydrochloric acid reacts with iron filings.

Ans. (1) Sulphuric acid + Zinc → Zinc sulphate + Hydrogen

H₂SO₄(aq) + Zn(s) → ZnSO₄(aq) + H₂(g)

(2) Hydrochloric acid + Magnesium → Magnesium chloride + Hydrogen

2HCl(aq) + Mg(s) → MgCl₂(aq) + H₂(g)

(3) Sulphuric acid + Aluminium → Aluminium sulphate + Hydrogen

3H₂SO₄(aq) + 2Al(s) → Al₂(SO4)₃(aq) + 3H₂(g)

(4) Hydrochloric acid + Iron → Ferric chloride + Hydrogen

6HCl(aq) + 2Fe(s) → 2FeCl₃(aq) + 3H₂(g)

25. Compounds such as alcohols and glucose also contain hydrogen but are not categorized as acids. Describe an activity to prove it.

Ans. Activity

Method

Step 1- Two nails are fitted on a cork and are kept in a 100 mL beaker.

Step 2- The nails are then connected to the two terminals of a 6-volt battery through a bulb and a switch.

Step 3- Some dilute HCl is poured into the beaker and the current is switched on.

Step 4- The same experiment is then performed with glucose solution and alcohol solution.

Observations:

It is observed that the bulb glows in the HCl solution but does not glow in the glucose solution and alcohol solution.

Result: HCl dissociates into H+(aq) and Cl−(aq) ions. These ions conduct electricity in the solution which results in the glowing of the bulb. On the other hand, the glucose solution and alcohol solution do not dissociate into ions. Therefore, it does not conduct electricity. (Refer to Active Chemistry 8 for figure).

Conclusion: From this activity, it can be concluded that all acids contain hydrogen but not all compounds containing hydrogen are acids.

Though alcohols and glucose contain hydrogen, they are not categorised as acids.

26. Why does distilled water not conduct electricity, whereas rain water does?

Ans. Distilled water is a pure form of water and is devoid of any ionic species. Therefore, it does not conduct electricity. Rain water, being an impure form of water, contains many ionic species such as acids and therefore, it conducts electricity.

27. Why do acids not show acidic behaviour in the absence of water?

Ans. Acids do not show acidic behaviour in the absence of water because there are no hydrogen ions available for conduction of electricity. Acids dissociate in the presence of water to give free hydrogen ions. It is the hydrogen ions that are responsible for the acidic behaviour.

28. Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9, respectively. Which solution is

(a) neutral

(b) strongly alkaline

(c) strongly acidic

(d) weakly acidic

(e) weakly alkaline?

Arrange the pH in increasing order of hydrogen-ion concentration.

Ans. (a) Neutral - Solution D with pH 7

(b) Strongly alkaline - Solution C with pH 11

(c) Strongly acidic - Solution B with pH 1

(d) Weakly acidic - Solution A with pH 4

(e) Weakly alkaline - Solution E with pH 9

The pH can be arranged in the increasing order of the concentration of hydrogen ions as 11 < 9 < 7 < 4 < 1.

29. 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?

Ans. The fizzing will occur strongly in test tube A, in which hydrochloric acid (HCl) is added. This is because HCl is a stronger acid than CH₃COOH and therefore, produces hydrogen gas at a faster speed due to which fizzing occurs.

30. Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.

Ans. The pH of milk is 6. As it changes to curd, the pH will reduce because curd is acidic in nature. The acids present in it decrease the pH.

31. 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?

Ans. (a) The milkman shifts the pH of the fresh milk from 6 to slightly alkaline because in alkaline condition, milk does not set as curd easily.

(b) Since this milk is slightly basic than usual milk, acids produced to set the curd are neutralised by the base. Therefore, it takes a longer time for the curd to set.

32. Plaster of Paris should be stored in a moisture-proof container. Explain why?

Ans. Plaster of Paris should be stored in a moisture-proof container because Plaster of Paris, a powdery mass, absorbs water (moisture) to form a hard solid known as gypsum.

33. What is a neutralisation reaction? Give two examples.

Ans. A reaction in which an acid and base react with each other to give a salt and water is termed as neutralisation reaction. In this reaction, energy is evolved in the form of heat.

For example,

(i) NaOH + HCl → NaCl + H2₂O

    Base + Acid → Salt + Water

(ii) During indigestion (caused due to the production of excess hydrochloric acid in the stomach), we use an antacid (generally, milk of magnesia, Mg(OH)₂ which is basic in nature). The antacid neutralises the excess of acids and thus, gives relief from indigestion.

    Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O

34. Give two important uses of washing soda and baking soda.

Ans. Two important uses of washing soda and baking soda are as follows:

(1) Washing soda

    (a) It is used in glass, soap, and paper industries.

    (b) It is used to remove permanent hardness of water.

(2) Baking soda

    (a) It is used as baking powder. Baking powder is a mixture of baking soda and a mild acid known as tartaric acid. When it is heated or mixed in water, it releases CO₂ gas that makes bread or cake fluffy.

    (b) It is used in soda-acid fire extinguishers.

Exercise -01

Multiple Choice Questions

1. Which of the following are present in a dilute aqueous solution of hydrochloric acid?

(1) H₃O⁺ + Cl⁻

(2) H₃O⁺ + OH⁻

(3) Cl⁻ + OH⁻

(4) unionised HCl

2. Which of the following is acidic in nature?

(1) Lime juice

(2) Human blood

(3) Lime water

(4) Antacid

3. Which one of the following is acidic?

(1) Lemon juice

(2) Tomatoes

(3) Curd

(4) All of these

4. Some fruits like mango, lemon, raw grapes, orange, etc., have a sour taste due to the presence of

(1) Acetic acid

(2) Citric acid

(3) Lactic acid

(4) Oxalic acid

5. Which among the following is not a base?

(1) NaOH

(2) KOH

(3) NH₄OH

(4) C₂H₅OH

6. Which one of the following will turn red litmus blue?

(1) Vinegar

(2) Soap

(3) Lemon juice

(4) Soft drinks

7. Which one of the following will turn blue litmus red?

(1) Vinegar

(2) Lime water

(3) Ammonium hydroxide solution

(4) Soap solution

8. Phenolphthalein is

(1) Pink in acidic medium, yellow in basic medium

(2) Yellow in acidic medium, pink in basic medium

(3) Colourless in acidic medium, pink in basic medium

(4) Pink in acidic medium, colourless in basic medium.

9. Which of the following statements is true for acids?

(1) Bitter and change red litmus to blue

(2) Sour and change red litmus to blue

(3) Sour and change blue litmus to red

(4) Bitter and change blue litmus to red

10. Which of the following indicators turn red in an acidic solution?

i. Phenolphthalein ii. Litmus

iii. Turmeric iv. Methyl orange

Choose the correct option:

(1) (i) and (ii)

(2) (ii) and (iii)

(3) Only (ii)

(4) (ii) and (iv)

11. Which one of the following is an olfactory indicator?

(1) Litmus

(2) Turmeric

(3) Vanilla essence

(4) All of these

12. Zinc granules on treating with an acid X, form the zinc sulphate (ZnSO₄) salt along with the evolution of a gas Y which burns with a pop sound when brought near to a burning candle. Identify the acid X and gas evolved Y.

(1) X- Sulphuric acid and Y- Oxygen gas

(2) X- Hydrochloric acid and Y- Oxygen gas

(3) X- Sulphuric acid and Y- Hydrogen gas

(4) X- Hydrochloric acid and Y- Hydrogen gas

13. Which of the following substance will not give carbon dioxide on treatment with dilute acid?

(1) Marble

(2) Limestone

(3) Baking soda

(4) Lime

14. Identify the products of the following reaction

CaCO₃ + HCl → ?

(1) Calcium hydrogen carbonate and chlorine gas

(2) Calcium chloride and water

(3) Calcium oxide, carbon dioxide and water

(4) Calcium chloride, carbon dioxide and water

15. The pH of the gastric juices released during digestion is

(1) less than 7

(2) more than 7

(3) equal to 7

(4) equal to 0

16. If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done?

(1) Wash the hand with saline solution.

(2) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate.

(3) After washing with plenty of water apply solution of sodium hydroxide on the hand.

(4) Neutralise the acid with a strong alkali.

17. To prevent tooth decay we are advised to brush our teeth regularly. The nature of the tooth paste commonly used is

(1) acidic

(2) neutral

(3) basic

(4) corrosive

18. An ant's sting can be treated with ________ which will neutralise the effect of the chemical injected by the ant's sting into our skin.

Choose the correct option from the following to be filled in the blank space:

(1) methanoic acid

(2) formic acid

(3) baking soda

(4) caustic soda

19. Which of the following is a basic salt?

(1) SnCl₂

(2) NaCl

(3) NH₄Cl

(4) CH₃COONa

20. Sodium carbonate is a basic salt because it is a salt of

(1) strong acid and strong base

(2) weak acid and weak base

(3) strong acid and weak base

(4) weak acid and strong base

21. Common salt besides being used in kitchen can also be used as the raw material for making

(i) washing soda

(ii) bleaching powder

(iii) baking soda

(iv) slaked lime

(1) (i) and (ii)

(2) (i), (ii) and (iv)

(3) (i) and (iii)

(4) (i), (iii) and (iv)

22. Identify the correct representation of reaction occurring during chloralkali process.

(1) 2 NaCl(l) + 2 H₂O(l) → 2 NaOH(l) + Cl₂(g) + H₂(g)

(2) 2 NaCl(aq) + 2 H₂O(aq) → 2 NaOH(aq) + Cl₂(g) + H₂(g)

(3) 2 NaCl(aq) + 2 H₂O(l) → 2 NaOH(aq) + Cl₂(aq) + H₂(aq)

(4) 2 NaCl(aq) + 2 H₂O(l) → 2 NaOH(aq) + Cl₂(g) + H₂(g)

23. Which of the following is represented by the formula NaHCO₃?

(1) Sodium carbonate

(2) Baking soda

(3) Sodium acetate

(4) Washing soda

24. One of the constituents of baking powder is sodium hydrogen carbonate, the other constituent is

(1) hydrochloric acid

(2) tartaric acid

(3) acetic acid

(4) sulphuric acid

25. Lime water is

(1) CaO

(2) Ca(OH)₂

(3) CaCO₃

(4) CaCl₂

26. Bleaching powder is used as a disinfectant for water to

(1) make water tastier

(2) remove all the dirt from water

(3) make water germ-free

(4) make water clear

27. Na₂CO₃ . 10 H₂O is

(1) Washing soda

(2) Baking soda

(3) Bleaching powder

(4) Tartaric acid

28. At what temperature is gypsum heated to form Plaster of Paris?

(1) 90°C

(2) 100°C

(3) 110°C

(4) 120°C

29. How many water molecules does Plaster of Paris contain?

(1) 1 ½

(2) ½

(3) 3

(4) 4

30. Copper sulphate crystals when heated strongly, lose their water of crystallization to give anhydrous copper sulphate accompanied by a change in color from:

(1) Blue to green

(2) Blue to white

(3) Blue to sky blue

(4) Blue to grey

Fill in the Blanks

• Sting of honey bee contain -
• A water-soluble base produce ions in solutions.
• An indicator changes its with change of the nature of the solution.
• Phenolphthalein gives a colour when added to sodium hydroxide solution.
• Blue litmus turns red when added to solution.
• A farmer treats the soil of his field with lime when the soil has nature.
• Milk of magnesia is used as .
• The pH of an acidic solution is than 7.
• Electrolysis of an aqueous solution of ___ produces hydrogen at cathode, chlorine at anode and sodium hydroxide in the solution.
• Hydrated copper sulphate contains five molecules of of crystallization.

Fill in the missing data in the following table

True or False

• Oxalic acid is present in bee sting.
• Litmus (indicator) is obtained from nettle plant.
• An indicator is a substance by which one can identify an acidic and basic solution.
• Lime water turns red litmus blue.
• Phenolphthalein is a natural indicator.
• The right temperature for heating gypsum during the manufacture of Plaster of Paris is 273 K.
• Plaster of Paris can be stored in any type of containers (open or closed or air tight).
• The aqueous solution of sodium chloride is acidic.
• Baking soda can be used to treat ant's sting.
• Common salt dissolved in water turns blue litmus red.

Match the Column

Match the chemical substances given in Column (I) with their appropriate application given in Column (II).

Match the acids given in Column (I) with their correct source given in Column (II)

Match the important chemicals given in Column (I) with the chemical formulae given in Column (II) :

Match the following columns :

Crossword Puzzle

Across

(1) Name of acid in softdrink.[8]

(3) Chemical containing hydroxide ions.[4]

(4) Chemical that is corrosive, has a sour taste and a pH less than 7.[4]

(6) Neutral substances have this pH.[5]

(7) Alkalis have a pH than 7.[4]

(9) Acid and base neutralise to form and water.[4]

(11) Household bases are suitable for .[8]

(13) Chemical with a soapy feel and pH more than 7. [6]

(15) Acids change blue litmus paper [3]

(18) Sulphuric acid turns litmus paper .[3]

(19) Salt has this pH.[5]

(21) Alkalis turn __ paper blue.[6]

(22) Carbon dioxide and water form acid.[8]

(25) Stomach acid.[12]

Down

(1) Many household __ products are bases.[8]

(2) Indicator made from lichens.[6]

(3) Chemical that neutralises an acid.[4]

(5) Chemical that changes colour in acids and bases.[9]

(8) Common indicator used in liquid or paper form.[6]

(10) Soluble base.[6]

(12) Common name for sodium hydroxide is

 soda.[7]

(14) Common name for calcium hydroxide.[9]

(16) Distilled water has this pH.[5]

(17) Acids have a pH that is than 7.[4]

(20) rain is an environmental problem in industrial areas.[4]

(23) Reacts with a metal to form hydrogen gas and a salt.[4]

(24) Measure of amount of hydrogen ions released in solution.[2]

Answer Key

Multiple Choice Questions

Fill in the blanks

• Formic acid
• hydroxide (OH−)
• colour
• pink
• a acidic
• acidic
• antacid
• less
• sodium chloride
• water

Fill in the missing data in the following table

True or False

1. False
2. False
3. True
4. True
5. False
6. False
7. False
8. False
9. True
10. False

Match the column

• (1) → (iii) ; (2) → (iv) ; (3) → (i) ; (4) → (ii)
• (1) → (iv) ; (2) → (iii) ; (3) → (ii) ; (4) → (i)
• (1) → (ii) ; (2) → (iii) ; (3) → (iv) ; (4) → (i)
• (1) → (iii) ; (2)→ (i) ; (3)→ (ii) ; (4) → (iv)

Crossword Puzzle

Exercise-02

Very Short Answer Type Questions

1. Name the acids present in (i) vinegar (ii) lemon (iii) orange.

2. How alkalis differ from bases? Explain.

3. Name any two natural indicators.

4. What colour change takes place when turmeric comes in contact with soap?

5. What are the colours shown by phenolphthalein in acidic medium and basic medium?

6. Usually which gas is liberated when acid reacts with metals?

7. Which gas is liberated when metal carbonates react with acids?

8. Will solution of glucose conduct electricity?

9. On what factor strength of acid and base depends?

10. What will happen to the concentration of [H⁺] ions in a solution if NaOH is added to water?

11. Which type of acid & base forms only the normal salts?

12. From the following, pick the acidic, basic and neutral salt.

(a) Sodium chloride

(b) Ammonium chloride

(c) Sodium acetate

 (d) Calcium carbonate

 13. Write one use of each of washing soda and baking soda.

 14. Define water of crystallization.

 15. What is the temperature required to convert gypsum into POP?

 Short Answer Type Questions

1. Write down the molecular formula for : Sulphuric acid, Nitric acid, Phosphoric acid, Carbonic acid.

2. Select the formulae of acids, bases and salts from the following list :

NaCl, NaOH, H₃PO₄, Na₂CO₃, Ca(OH)₂, CuSO₄.5H₂O, H₂SO₄, H₂CO₃, HCl, NaHCO₃, Na₂CO₃.10H₂O, Al(OH)₃, KCl.

3. For diluting an acid the acid should be poured carefully in water and not the reverse. Why?

4. What will be the action of the following substances on litmus paper?

Dry HCl gas, Moistened NH3 gas, Lemon juice, Carbonated soft drink, Curd, Soap solution.

5. Why HCl gas is unable to change the colour of dry blue litmus paper? What happens if the litmus paper is moistened?

6. When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.

7. Name the gas evolved when dilute sulphuric acid reacts with sodium carbonate. Write the chemical equation for the reaction involved.

8. What happens when nitric acid is added to egg shell?

9. What does pH stand for? What does a pH scale indicate?

10. Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.

11. A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since both the solutions are colourless, how will she distinguish between the two?

12. What happen when electric current is passed through brine? Give reaction.

13. How would you distinguish between baking powder and washing soda by heating?

14. How is Plaster of Paris obtained? What reaction is involved in the setting of a paste of Plaster of Paris?

15. A blue salt becomes white on heating. With the help of a reaction explain the change in colour.

Long Answer Type Questions

1. Dry HCl gas does not affect a dry blue litmus paper, whereas it changes a moist blue litmus paper to red. Explain.

2. (a) What will you observe when dil. HCl is added to a small amount of copper oxide in a beaker? (b) Aqueous solution of HCl shows acidic character. But the aqueous solution of glucose fails to do so. Why? (c) Why curd and sour substances should not be kept in brass and copper vessels?

3. A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y , it gives a compound Z , used for disinfecting drinking water. Identity X, Y, G and Z.

4. Identify the compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C.

5. Discuss chlor-alkali process for manufacturing sodium hydroxide.

6. A sanitary worker uses a white chemical having strong smell of chlorine gas to disinfect the water tank.

(i) Identify the compound.

(ii) Write the chemical equation for its preparation.

(iii) Write its uses.

7. For making cake, baking powder is taken. If at home your mother uses baking soda instead of baking powder in cake,

(a) How will it affect the taste of the cake and why?

(b) How can baking soda be converted into baking powder?

(c) What is the role of tartaric acid added to baking soda?

8. A compound of sodium is used in kitchen to make pakoras crispy. It is also used to remove acidity in stomach.

(i) Identify the compound.

(ii) State how it is manufactured.

(iii) Write an equation to show the effect of heat on this compound.

(iv) Write its uses.

9. What is plaster of Paris? How is it prepared? Give the chemical equation.

10. Comment on the statement : Are the crystals of salts really dry?

Multiple Choice Questions

1. Option (1)

According to Arrhenius theory, "An acid is a substance which when dissolved in water, ionizes and releases hydrogen ions [H⁺(aq)] in solution". It further combines with water to form hydronium ion [H₃O⁺(aq)].

HCl + H₂O → H₃O⁺ + Cl⁻

2. Option (1)

Lime juice contains citric acid.

3. Option (4)

Lemon juice, tomatoes, curd all are acidic in nature.

4. Option (2)

Citrus fruits contain citric acid.

5.Option (4)

Ethanol (C₂H₅OH) doesn't give OH⁻ (hydroxide ions) in aqueous medium.

6. Option (2)

Soap is basic in nature, will turn red litmus blue.

7. Option (1)

Vinegar is acidic in nature, will turn blue litmus red.

8. Option (3)

Phenolphthalein is colourless in acidic medium, pink in basic medium.

9. Option (3)

Acid has a sour taste, it turns blue litmus to red.

10. Option (4)

Methyl orange and blue litmus both turn red in acidic solution.

11. Option (3)

An Olfactory indicator is a substance whose smell varies depending on whether it is mixed with an acidic or basic solution. Olfactory indicators can be used in the laboratory to test whether a solution is a base or an acid, a process called olfactory titration. Onion, clove oil and vanilla extract are examples. An olfactory indicator works on the principle that when an acid or base is added to it, then different odour can be detected in bases and in acids.

12. Option (3)

Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g)

13. Option (4)

Except lime all have carbonate anion so after treatment with acid all produces CO₂ gas.

14. Option (4)

CaCO₃ + HCl → CaCl₂ + CO₂ + H₂O

15. Option (1)

The pH of gastric juices is less than 7 in the human stomach.

16. Option (2)

Sodium hydrogen carbonate is a weak base so it is used to neutralize the acid.

17. Option (3)

Nature of tooth paste should be basic to neutralize the acidic nature of mouth.

18. Option (3)

Sodium hydrogen carbonate is a weak base so it is used to neutralize the acid.

19. Option (4)

CH₃COONa it is made by weak acid CH₃COOH and strong base NaOH.

20. Option (4)

Strong base is NaOH Weak acid is H₂CO₃

21. Option (3)

Washing soda is prepared from NaCl by Solvay process. NaHCO₃ may be obtained by the reaction of carbon dioxide and ammonia with aqueous solution of sodium chloride.

22. Option (4)

The chloralkali process - production of sodium hydroxide, chlorine and hydrogen from sodium chloride is known as chloralkali process.

2 NaCl(aq) + 2 H₂O(l) → 2 NaOH(aq) + Cl₂(g) + H₂(g)

23. Option (2)

Baking soda is sodium hydrogen carbonate or sodium bicarbonate.

24. Option (2)

Baking powder is a mixture of baking soda (sodium hydrogen carbonate) and a mild edible acid like tartaric acid.

25. Option (2)

CaO + H₂O → Ca(OH)₂

26. Option (3)

Bleaching powder is used as disinfectant for water to make it germ-free.

27. Option (1)

Na₂CO₃ ⋅ 10 H₂O - Washing soda.

28. Option (2)

On heating at 100°C, gypsum gives plaster of Paris.

29. Option (2)

CaSO₄ ⋅ ½ H₂O (plaster of Paris).

30. Option (2)

CuSO₄ ⋅ 5 H₂O - Blue

Anhydrous Copper sulphate (CuSO₄) White

True or False

1. False

Bee sting contains formic acid.

2. False

A water-soluble purple powder derived from certain lichens that changes to red with increasing acidity and to deeper blue with increasing basicity.

3. True

Indicates the nature of particular solution whether acidic, basic or neutral.

4. True

Lime water is basic in nature.

5. False

It is a synthetic indicator.

6. False

The right temperature for heating gypsum during the manufacture of plaster of Paris is 373 K.

7. False

Plaster of Paris is water and heat sensitive, so it should be stored in closed or air tight container.

8. False

An aqueous solution of NaCl is neutral (pH=7).

9. True

It is used to treat ant's sting.

10. False

Common salt in water forms neutral solution, which doesn't have any effect on litmus.

Exercise-02 (Solutions)

Very Short Answer Type Questions

1. (i) Vinegar - acetic acid

(ii) Lemon - citric acid

(iii) Orange - citric acid

2. Bases are substances that react with acids and neutralise them. They are usually metal oxides, metal hydroxides, metal carbonates or metal hydrogen carbonates. Many bases are insoluble; they do not dissolve in water. If a base does dissolve in water, we call it an alkali.

3. Litmus, China rose, turmeric etc.

4. It changes from yellow to reddish brown.

5. Phenolphthalein remains colourless in acidic medium while turns pink in basic medium.

6. Hydrogen gas.

7. CO₂ gas. Acid + Metal carbonate → Salt + H₂O + CO₂

8. No, glucose solution cannot conduct electricity due to the absence of ions.

9. On the basis of degree of dissociation.

10. Concentration decreases, therefore pH for acids increases and for alkalis pH decreases.

11. Strong acid and strong base or weak acid and weak base.

12. (a) NaCl - Neutral salt

(b) NH₄Cl - Acidic salt

(c) CH₃COONa - Basic salt

(d) CaCO₃ - Basic salt

13. Use of washing soda

Washing soda (or sodium carbonate) is used for washing clothes (laundry purposes).

Use of sodium hydrogen carbonate (NaHCO₃)

As an ingredient in antacids. Being alkaline, it neutralises excess acid in the stomach and provides relief.

14. The water associated with the crystal (or molecule) of any salt is called water of crystallisation.

The salt containing water of crystallisation are called hydrated salts.

15. 100°C or 373 K.

Short Answer Type Questions

1. Sulphuric acid - H₂SO₄

Nitric acid - HNO₃

Phosphoric acid - H₃PO₄

Carbonic acid - H₂CO₃

2. Acids: H₃PO₄, HCl, H₂SO₄, H₂CO₃

Bases : NaOH, Ca(OH)₂, Al(OH)₃

Salts : NaCl, Na₂CO₃, CuSO₄.5H₂O, NaHCO₃, Na₂CO₃.10H₂O, KCl

3. It is recommended that the acid should be added to water and not water to the acid because the process of dissolving an acid in water is exothermic. If water is added to acid, since a large amount of acid is present, a large amount of heat is generated. Therefore, the mixture splashes out and causes burns.

4. (i) Dry HCl gas - no effect.

(ii) Moistened NH₃ gas - red to blue.

(iii) Lemon juice - blue to red.

(iv) Carbonated soft drink - blue to red.

(v) Curd - blue to red.

(vi) Soap solution - red to blue.

5. Acid does not ionize in the absence of water to liberate H₃O⁺ which shows the acidic nature of a solution. Therefore, dry HCl gas does not change the colour of the dry litmus paper because it does not contain H⁺ ions. In the presence of moisture, HCl dissociates into H⁺ ions and will turn blue litmus red.

6. Zinc metal gives hydrogen gas when it is treated with dilute sulphuric acid. Hydrogen gas is utilized in the hydrogenation of oil.

Zn + H₂SO₄ → ZnSO₄ + H₂

Test for hydrogen gas: When a burning candle is brought near the hydrogen gas, it burns with a pop sound which confirms the presence of hydrogen gas.

7. Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂

CO₂ gas is evolved.

8. Eggshell is made of calcium carbonate. We know that when calcium carbonate reacts with nitric acid, it gives carbon dioxide, calcium nitrate and water. The same reaction happens when nitric acid is poured over the eggshell.

CaCO₃ + 2HNO₃ → Ca(NO₃)₂ + CO₂ + H₂O

9. "Potential of Hydrogen". This is what pH stands for. pH is a measure of the acidity or basicity of an aqueous solution. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline. Pure water has a pH very close to 7.

10. Name of acid present in ant sting: Methanoic acid 

Chemical Formula of methanoic acid: HCOOH. Method to get relief from the discomfort caused by the ant sting: Rubbing baking soda over the location of the ant sting. Explanation: Since baking soda is a base, thus by rubbing over the ant sting it neutralizes the methanoic acid present in the ant sting and gives relief from pain.

11. We can use phenolphthalein to check which of the beakers contains acid and which one contains a base. Apart from that, we can also use other natural indicators, like China rose or turmeric.

12. When electricity is passed through an aqueous solution of brine (NaCl), sodium hydroxide is formed along with the liberation of hydrogen gas at the cathode and chlorine gas at the anode.

13. The production of carbon dioxide is the main characteristic of baking powder that makes it suitable for baking. Baking powder gives carbon dioxide and water vapour on heating at even low temperatures such as 100°C. The gas so formed turns lime water milky, which confirms the presence of carbon dioxide gas.

2NaHCO₃ + Heat → Na₂CO₃ + CO₂ + H₂O

When Washing soda is heated, it does not produce carbon dioxide even at high temperatures, such as 200°C or 300°C. However, washing soda gives sodium carbonate and becomes hemihydrate.

The gas produced by the heating of the samples can be checked by passing it through lime water. If the lime water turns milky, then the evolved gas is carbon dioxide and the heated substance is baking powder.

14. The gypsum is heated to about 100°C to remove its H₂O (water) content. It becomes a dry powder, with the chemical name calcium sulphate hemihydrate.

CaSO₄.2H₂O → CaSO₄.1/2H₂O + 3/2H₂O (at 100°C)

Setting process of POP is CaSO₄.1/2H₂O(s) + 3/2H₂O(l) → CaSO₄.2H₂O(s)

15. Actually, blue salt of copper sulphate is chemically copper sulphate penta hydrate (CuSO₄.5H₂O). The blue colour is due to these 5 moles of water. By heating, this water evaporates, leaving CuSO₄ which is colourless.

CuSO₄.5H₂O(s) ⇌ CuSO₄(s) + 5H₂O(l)

(blue solid)          (dirty white solid)

Long Answer Type Questions

1. Acid does not ionize in the absence of water to liberate H₃O⁺ which shows the acidic nature of a solution. Therefore, dry HCl gas does not change the colour of the dry litmus paper because it does not contain H⁺ ions. In the presence of moisture, HCl dissociates into H⁺ ions and will turn blue litmus red.

2. (a) Metal oxides react with acids to form salt and water.

Metal oxide + Acid → Salt + Water

CuO + 2HCl → CuCl₂ + H₂O

Copper(II) oxide Hydrochloric acid Copper(II) chloride Water

(Black)(Blue green)

This shows that metal oxides are basic in nature.

Some more examples:

(i) CaO(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l)

(ii) MgO(s) + H₂SO₄(aq) → MgSO₄(aq) + H₂O(l)

(b) As electric current is carried through the solution by ions, this shows that acids dissociate in the solution to produce H⁺(aq) ions, but substances like glucose and alcohol do not dissociate to give H⁺ ions and hence are not acidic. Thus, H⁺ ions are responsible for the acidic properties.

(c) Curd and other sour substances contain acids. Therefore, when they are kept in brass and copper vessels, the metal reacts with the acid to liberate hydrogen gas and harmful products, thereby spoiling the food.

3. Calcium carbonate gives carbon dioxide gas when it reacts with hydrochloric acid.

CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O

Carbon dioxide turns lime water milky when passed through it because of the formation of calcium carbonate. When carbon dioxide, so formed, is passed through lime water, lime water turns milky because of the formation of calcium carbonate.

CO₂ + Ca(OH)₂ → CaCO₃ + H₂O

On the electrolysis of brine, chlorine gas is deposited over the anode, which gives calcium oxychloride (Bleaching powder) on passing over slaked lime. The bleaching powder is used in disinfecting drinking water.

Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O

Therefore; Metal carbonate 'X' is calcium carbonate.

Solution 'Y' is lime water (Calcium hydroxide).

Gas 'G' is chlorine gas.

Dry 'Y' is dry calcium hydroxide (dry slaked lime).

Compound 'Z' is bleaching powder (Calcium oxy chloride).

4. X = NaOH

A = Na₂ZnO₂

B = NaCl

C = CH₃COONa

5. Chlor-alkali process for obtaining sodium hydroxide

When we pass electricity through a solution of sodium chloride, commonly called brine, it decomposes to form sodium hydroxide according to the following equation:

2NaCl(aq) + 2H₂O(l) → 2NaOH(aq) + Cl₂(g) + H₂(g) (Electric Current)

On electrolysis, chlorine gas is formed at the anode and hydrogen at the cathode; sodium hydroxide solution is formed near the cathode. All these products are commercially important.

6. (i) Compound is bleaching powder.

(ii) Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O

    Slaked lime   Bleaching powder

(iii) Uses of bleaching powder:

    (a) For bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry.

    (b) As an oxidising agent in many chemical industries.

    (c) For disinfecting drinking water to make it free of germs.

7. (a) The chemical name of baking soda is sodium bicarbonate, which gives sodium carbonate, carbon dioxide and water on heating. If baking soda is used instead of baking powder in the making of cake, the formation of sodium carbonate would make the taste of the cake bitter.

    2NaHCO₃ + Heat → Na₂CO₃ + CO₂ + H₂O

(b) By mixing an edible acid, usually tartaric acid, baking soda is converted into baking powder. Other mild edible acids can also be used instead of tartaric acid.

(c) Tartaric acid gives hydrogen ions when water is added to it. The hydrogen ions produced by tartaric acid react with sodium bicarbonate and give carbon dioxide, which makes the dough soft and spongy. If sodium carbonate is formed because of heating, tartaric acid neutralizes it and forms sodium tartarate, which has a pleasant smell and good taste.

    2NaHCO₃ + C₄H₆O₆ → 2CO₂ + 2H₂O + Na₂C₄H₄O₆

8. (i) Baking soda

(ii) By the Solvay process, it is an intermediate product.

(iii) 2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O (Δ)

(iv) Uses of sodium hydrogen carbonate (NaHCO₃):

(a) For making baking powder, which is a mixture of baking soda (sodium hydrogen carbonate) and a mild edible acid like tartaric acid. When baking powder is mixed with water, the following reaction takes place:

NaHCO₃ + H⁺ → CO₂ + H₂O + Sodium salt of the acid

(from acid)

Carbon dioxide so produced during the reaction is responsible for making the bread and cake rise, making them soft and spongy.

(b) As an ingredient in antacids. Being alkaline, it neutralises excess acid in the stomach and provides relief.

(c) It is used in soda-acid fire extinguishers.

9. Plaster of Paris (CaSO₄.1/2H₂O)

Plaster of Paris is hemihydrate (hemi means half and hydrate means water) of calcium sulphate. Its molecular formula is CaSO₄.1/2H₂O or (CaSO₄)₂.H₂O.

In Plaster of Paris, one molecule of water is shared by two formula units of CaSO₄ as,

Preparation of Plaster of Paris

Plaster of Paris is obtained by heating gypsum (CaSO₄ .2H₂O) in a kiln at 373 K (or 100°C).

2[CaSO₄ . 2H₂O](s)  --Heat at 373 K (100°C)-->  (CaSO₄)₂ . H₂O(s) + 3H₂O(g)

${\text{CaSO}}_4\cdot 2{\text{H}}_2\text{O}(s)\underset{\text{heat}}{\overset{373\text{K},(100^{\circ }\text{C})}{\to }}{\text{CaSO}}_4\cdot \frac{1}{2}{\text{H}}_2\text{O}(s)+\frac{3}{2}{\text{H}}_2\text{O}(g)$

During the preparation of Plaster of Paris, careful control of temperature is crucial. If the temperature exceeds 373 K, anhydrous calcium sulphate (CaSO₄) will be formed instead of the desired hemihydrate.

The reaction is as follows:

CaSO₄ · 2H₂O(s)  --(More than 373 K)-->  CaSO₄(s) + 2H₂O(g)

(Gypsum)  (Anhydrous Calcium Sulphate - Dead burnt plaster)

10. Crystals of some salts contain a specific amount of water molecules associated within their crystal structure. This associated water is termed the water of crystallisation. Salts that incorporate water of crystallisation are known as hydrated salts.

11. Aim: To test for the presence of water of crystallisation in copper sulphate crystals.

12. Materials Required:

Boiling tube

Copper sulphate crystals

Burner

Water

Test tube holder

13. Method:

(i) Take a few crystals of copper sulphate and place them in a dry boiling tube.

(ii) Heat the boiling tube gently using a burner. Observe and note any change in the colour of the copper sulphate crystals.

(iii) Carefully observe the inner walls of the boiling tube for the appearance of any water droplets.

(iv) Allow the heated copper sulphate sample to cool. Once cooled, add 2-3 drops of water to the sample. Observe any changes.

Removing Water of Crystallisation

Now answer:

(i) What do you observe on heating blue copper sulphate crystals?

(ii) Is the blue colour of copper sulphate restored on adding water?

Observation and discussion:

Blue coloured copper sulphate crystals, upon heating, leave behind white anhydrous copper sulphate. Water droplets are observed in the upper, cooler parts of the boiling tube. When 2-3 drops of water are added to the white residue, the blue colour reappears.

Conclusion:

Copper sulphate crystals, when heated, lose water to form white anhydrous copper sulphate. This white anhydrous copper sulphate can combine again with water to reform the blue coloured copper sulphate crystals.

Water of crystallisation is the fixed number of water molecules present in one formula unit of a crystalline salt. For example:

Blue vitriol: CuSO₄ . 5H₂O

Green vitriol: FeSO₄ . 7H₂O

Glauber's salt: Na₂SO₄ . 10H₂O

White vitriol: ZnSO₄ . 7H₂O

Gypsum: CaSO₄ . 2H₂O

Epsom salt: MgSO₄ . 7H₂O

7.0Benefits of Chapter 2 Acid, Bases and Salts in NCERT Solutions Class 10

• These solutions provide detailed explanations of fundamental concepts related to acids, bases, and salts. This helps students build a strong foundation in chemistry.
• NCERT solutions are aligned with the CBSE syllabus, making them essential for exam preparation.
• The solutions explain various chemical reactions involving acids, bases, and salts, including neutralization reactions and reactions with metals.
• NCERT solutions serve as a valuable tool for reinforcing classroom learning.