CBSE Class 10 Science Chapter-2 Acids, Bases and Salts Notes & NCERT Solution

Key Point Chapter 2: Acids, Bases, and Salts

Acids:

1. Definition: Acids are substances that taste sour, turn blue litmus paper red, and have the ability to donate protons (H⁺ ions).
2. Common Acids:
   • Hydrochloric acid (HCl)
   • Sulfuric acid (H₂SO₄)
   • Nitric acid (HNO₃)
   • Acetic acid (CH₃COOH)

Bases:

1. Definition: Bases are substances that taste bitter, feel soapy, turn red litmus paper blue, and have the ability to accept protons (H⁺ ions).
2. Common Bases:
   • Sodium hydroxide (NaOH)
   • Potassium hydroxide (KOH)
   • Ammonium hydroxide (NH₄OH)

Salts:

1. Formation of Salts:
   • Salts are formed by the neutralization reaction between acids and bases.
   • The general equation for this reaction is: Acid + Base → Salt + Water
2. Types of Salts:
   • Neutral salts: Formed from a strong acid + strong base.
   • Basic salts: Formed from a weak acid + strong base.
   • Acidic salts: Formed from a strong acid + weak base.
   • Double salts: Contain two different cations or two different anions.
   • Example: Mohr’s salt (FeSO₄.(NH₄)₂SO₄.6H₂O)

pH Scale:

1. Definition: The pH scale measures the acidity or basicity of a solution. It ranges from 0 to 14.
   • 0-6: Acidic
   • 7: Neutral
   • 8-14: Basic
2. Calculation of pH:
   • pH=−log⁡[H+]pH=−log[H+]

Indicators:

1. Definition: Indicators are substances that change color with a change in pH.
2. Common Indicators:
   • Litmus paper (Red in acid, Blue in base)
   • Phenolphthalein (Colorless in acid, Pink in base)
   • Methyl orange (Red in acid, Yellow in base)

Chemical Properties:

1. Action of Acids on Metals:
   • Acids react with metals to produce salt and hydrogen gas.
   • 2HCl+Zn→ZnCl2+H22HCl+Zn→ZnCl2​+H2​
2. Action of Bases on Metals:
   • Bases also react with metals to produce salt and hydrogen gas.
   • 2NaOH+Zn→Na2ZnO2+H22NaOH+Zn→Na2​ZnO2​+H2​

Uses of Acids, Bases, and Salts:

1. Acids:
   • Used in the production of fertilizers.
   • Used in the laboratory for various experiments.
   • Used in the pharmaceutical industry.
2. Bases:
   • Used in the manufacturing of soaps and detergents.
   • Used in the preparation of medicines.
   • Used in the food industry.
3. Salts:
   • Used in the preservation of food.
   • Used in water softeners.
   • Used in the preparation of various chemicals.

Important Notes:

1. Self-ionization of Water:
   • 2H2O⇌H3O++OH−2H2​O⇌H3​O++OH−
2. Amphiprotic Substance:
   • Substances that can act as both acids and bases. Water is an example.
   • H2O+NH3⇌NH4++OH−H2​O+NH3​⇌NH4+​+OH−

These are some key points from Chapter 2 of Class 10 Science, providing an overview of acids, bases, and salts, their properties, reactions, and applications. For detailed explanations and further understanding, it is recommended to refer to your textbook and class notes.

CBSE Class 10 Science Notes Chapter 2 Acids Bases and Salts

Indicators: Indicators are substances that reveal the acidic or basic nature of a solution through color changes. There are different types of indicators:

1. Natural Indicators:
   • Obtained from natural sources.
   • Examples include litmus, turmeric, red cabbage, and China rose.
   • Litmus is purple; turns red with acids and blue with bases.
   • Turmeric is yellow; turns reddish-brown with bases, no change with acids.
   • Red cabbage juice is originally purple; turns reddish with acids and greenish with bases.
2. Olfactory Indicators:
   • Substances that change smell when mixed with acid or base.
   • Examples include onion and vanilla.
   • Onion loses smell with a base, no change with acids.
   • Vanilla smell vanishes with a base, no change with acids.
   • Used for visually impaired students in laboratories.
3. Synthetic Indicators:
   • Synthesized in the laboratory.
   • Examples include phenolphthalein, methyl orange.
   • Phenolphthalein is colorless, turns pink with bases.
   • Methyl orange is orange, turns red with acids and yellow with bases.

Acids:

• Sour taste, turn blue litmus red, release H+ ions in water.
• Examples: Sulphuric acid (H2SO4), Acetic Acid (CH3COOH), Nitric Acid (HNO3).
• Properties:
  • Sour taste.
  • Turn blue litmus red.
  • Conduct electricity.
  • Release H+ ions in aqueous solution.
• Types of Acids:
  1. Natural Acids:
     • Obtained from natural sources.
     • Examples: Methanoic acid, Acetic acid, Citric acid, Lactic acid.
  2. Mineral Acids:
     • Prepared from minerals.
     • Examples: Hydrochloric acid, Sulphuric acid, Nitric acid.
• Chemical Properties of Acids:
  1. Reaction with Metals:
     • Metal + Acid → Salt + Hydrogen.
     • Examples: HCl + Zn → ZnCl2 + H2.
  2. Reaction with Metal Carbonates:
     • Metal carbonate + Acid → Salt + Carbon dioxide + Water.
     • Examples: HCl + Na2CO3 → NaCl + CO2 + H2O.
  3. Reaction with Metal Hydrogen Carbonates:
     • Acid + Metal hydrogen carbonate → Salt + Carbon dioxide + Water.
     • Example: H2CO3 + NaHCO3 → Na2CO3 + CO2 + H2O.

Bases:

• Bitter taste, feel soapy, turn red litmus blue, give OH- ions in water.
• Examples: Sodium hydroxide (NaOH), Calcium hydroxide (Ca(OH)2).
• Properties:
  • Bitter taste.
  • Soapy to touch.
  • Turns red litmus blue.
  • Conducts electricity.
  • Releases OH- ions in Aqueous Solution.
• Chemical Properties of Bases:
  1. Reaction with Metals:
     • Alkali + Metal → Salt + Hydrogen.
     • Examples: NaOH + Zn → Na2ZnO2 + H2.
  2. Reaction with Oxides of Non-metals:
     • Base + Non-metal oxide → Salt + Water.
     • Examples: Ca(OH)2 + CO2 → CaCO3 + H2O.
  3. Neutralization Reaction:
     • Acid + Base → Salt + Water.
     • Examples: HCl + NaOH → NaCl + H2O.
  4. Reaction with Metal Oxides:
     • Acid + Metal Oxide → Salt + Water.
     • Examples: 2HCl + ZnO → ZnCl2 + H2O.

Common Properties:

• Acids give hydrogen gas with metals.
• Bases dissociate hydroxide ions in water, responsible for their basic behavior.

Dilution of Acid and Base:

• Dilution is exothermic.
• Acid or base is added to water; not water to acid/base.

Strength of Acid and Base:

• Strong acids completely ionize (e.g., HCl, H2SO4).
• Weak acids partially ionize (e.g., CH3COOH, H2CO3).

pH Scale:

• pH < 7: Acidic solution.
• pH > 7: Basic solution.
• pH = 7: Neutral solution.
• Universal Indicator: Shows a range of colors based on pH.

Some Important Compounds and their Uses:

1. Common Salt (Sodium Chloride):
   • Used to enhance food taste.
   • Manufacture of chemicals.
2. Sodium Hydroxide (Caustic Soda):
   • Strong base used in various industries.
3. Bleaching Powder (CaOCl2):
   • Disinfectant, bleaching agent, weed killer.
4. Baking Soda (NaHCO3):
   • Used in cooking, antacid, toothpaste.
5. Washing Soda (Sodium Carbonate):
   • Cleaning agent, in the textile and glass industry.
6. Plaster of Paris:
   • Used in medical casts, making molds.

Equations of Reactions:

• Acid + Metal → Salt + Hydrogen.
• Acid + Metal Carbonate → Salt + Carbon Dioxide + Water.
• Acid + Metal Hydrogen Carbonate → Salt + Carbon Dioxide + Water.
• Base + Non-metal Oxide → Salt + Water.
• Acid + Base → Salt + Water.
• Acid + Metal Oxide → Salt + Water.

Here are the NCERT Solutions for Class 10 Science Chapter 2 – Acids and Bases:

Acids, Bases, and Salts:

1. Acids, Bases And Salts:

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: I will dip the red litmus paper into each test tube. If the litmus paper turns blue, it indicates a basic solution. If it remains red, it indicates an acidic solution. Litmus paper doesn’t change color in the case of a neutral solution (like distilled water).

Q2: You have a solution of a substance. How will you verify whether it is acidic, basic, or neutral?

Answer: To determine the nature of the solution:

• I will use blue and red litmus paper.
• If blue litmus turns red, the solution is acidic.
• If red litmus turns blue, the solution is basic.
• If there is no change in color, the solution is neutral.

Q3: Why should curd and sour substances not be kept in brass and copper vessels?

Answer: Curd and sour substances contain acids. Brass and copper vessels react with acids to form toxic compounds, which can be harmful if consumed. Therefore, curd and sour substances should not be kept in brass and copper vessels.

2. Understanding The Chemical Properties Of Acids And Bases:

Q1: A solution turns red litmus blue. Is it a base or an acid?

Answer: A solution that turns red litmus blue is a base.

Q2: What is the action of the saliva on the following substances: a) Blue litmus paper b) Turmeric paper

Answer: a) Blue litmus paper: The saliva does not change the blue litmus paper, indicating that saliva is neutral. b) Turmeric paper: The saliva turns turmeric paper brown, indicating that saliva is slightly acidic.

3. What Do All Acids And All Bases Have In Common?:

Q1: Why do HCl, HNO3, etc., show acidic characters in aqueous solutions?

Answer: HCl (hydrochloric acid), HNO3 (nitric acid), etc., show acidic characters in aqueous solutions because they release hydrogen ions (H+) when dissolved in water. The presence of hydrogen ions imparts acidic properties to these substances.

Q2: If you hold a piece of blue litmus paper over the gas flame, what would happen to it?

Answer: If blue litmus paper is held over a gas flame, it will not show any change in color. The flame is neutral, and it does not turn litmus paper either red or blue.

4. How Strong Are Acid Or Base Solutions?:

Q1: What happens to the color of the litmus solution if a drop of an acid is added to it?

Answer: If a drop of acid is added to the litmus solution, the solution will turn red.

Q2: What will happen if a solution of an acid is mixed with a solution of a base in a test tube?

Answer: When a solution of an acid is mixed with a solution of a base in a test tube, a neutralization reaction takes place. The acidic and basic properties are neutralized, and the resulting solution is neither acidic nor basic but neutral.

5. More About Salts:

Q1: Why do acids not show acidic behavior in the absence of water?

Answer: Acids show acidic behavior in the presence of water because they release hydrogen ions (H+) when dissolved in water. In the absence of water, there is no medium for the dissociation of hydrogen ions, and thus, acids do not exhibit acidic behavior.

Q2: How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?

Answer: The concentration of hydronium ions (H3O+) decreases when a solution of an acid is diluted. Dilution involves adding more water to the acid, reducing the concentration of H+ ions and making the solution less acidic.

Here are the solutions to the intext questions from the mentioned pages of NCERT Class 10 Science Chapter 2:

Page Number: 18

Question 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?

Answer: (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.

Page Number: 22

Question 1: Why should curd and sour substances not be kept in brass and copper vessels?

Answer: Curd and sour substances should not be kept in brass and copper vessels because these and other sour food-stuffs contain acids which can react with the metal of the vessel to form poisonous metal compounds which can cause food poisoning and affect our health adversely.

Question 2: 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?

Answer: (i) Hydrogen (H2) gas is liberated when an acid reacts with a metal. (ii) Illustration: Set up the apparatus as shown in the given figure. Take some zinc granules in the test tube. Add about 5 mL dilute hydrochloric acid slowly. Soon the reaction between zinc and hydrochloric acid starts and hydrogen gas is evolved. (iii) Test for H2 gas: H2 gas is not soluble in water. When passed through soap solution, it gets trapped into bubbles. Bring a burning candle near the soap bubble filled with gas. The soap bubble bursts, and hydrogen gas burns with a pop sound.

Question 3: 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.

Answer: As the end product is calcium chloride and the gas formed is carbon dioxide, the metal compound A must be calcium carbonate. Therefore, the reaction between calcium carbonate and hydrochloric acid is:

CaCO3+2HCl→CaCl2+CO2+H2OCaCO3​+2HCl→CaCl2​+CO2​+H2​O

Page Number: 25

Question 1: Why do HCl, HNO3, etc show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?

Answer: H+ ions in aqueous solution are responsible for acidic character. HCl, HNO3, etc. give H+ ions in water while alcohol and glucose do not give H+ ion in water. Therefore, alcohol and glucose do not show acidic character.

Question 2: Why does an aqueous solution of an acid conduct electricity?

Answer: The aqueous solution of an acid conducts electricity due to the presence of charged particles called ions in it.

Question 3: Why does dry HCl gas not change the colour of the dry litmus paper?

Answer: Dry HCl gas does not give H+ ions and therefore does not change the colour of dry litmus paper.

Question 4: While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

Answer: While diluting an acid it is recommended that the acid should be added to water and not water to the acid because if water is added to concentrated acid to dilute it, then a large amount of heat is evolved at once. This heat changes some of the water to steam explosively which can splash the acid on one’s face or clothes and cause acid burns.

Question 5: How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?

Answer: When a given amount of an acid is added to water, there is a fixed number of hydronium ions per volume of the solution. On dilution, the number of hydronium ions per volume decreases and concentration decreases.

Question 6: How is the concentration of hydroxide ions (OH–) affected when excess base is dissolved in a solution of sodium hydroxide?

Answer: The concentration of hydroxide ions will increase when excess base is dissolved in a solution of sodium hydroxide, but it happens to a limited extent only after which the concentration becomes almost constant.

Page Number: 28

Question 1: 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?

Answer: A pH value of less than 7 indicates an acidic solution, while greater than 7 indicates a basic solution. Since solution A has more hydrogen ion concentration, solution A is acidic and solution B is basic.

Question 2: What effect does the concentration of H+ (aq) ions have on the nature of the solution?

Answer: More the concentration of H+ ions, higher the acidic nature of the solution.

Question 3: Do basic solutions also have H+ (aq) ions? If yes, then why are these basic?

Answer: Basic solutions have H+ (aq) ions. But these are far less in number than OH– ions that is responsible for their basic nature.

Question 4: 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)?

Answer: If the soil is too acidic (having low pH) then it is treated with materials like quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate).

Page Number: 33

Question 1: What is the common name of the compound CaOCl2?

Answer: Bleaching powder.

Question 2: Name the substance which on treatment with chlorine yields bleaching powder.

Answer: Slaked lime Ca(OH)₂.

Question 3: Name the sodium compound which is used for softening hard water.

Answer: Sodium carbonate.

Question 4: What will happen if a solution of sodium hydrogen carbonate is heated? Give the equation of the reaction involved.

Answer: Solution of sodium hydrogen carbonate on heating gives sodium carbonate and carbon dioxide gas is evolved. 2NaHCO3→Na2CO3+CO2+H2O2NaHCO3​→Na2​CO3​+CO2​+H2​O

Question 5: Write an equation to show the reaction between plaster of Paris and water.

Answer: CaSO4⋅1/2H2O+3/2H2O→CaSO4⋅2H2OCaSO4​⋅1/2H2​O+3/2H2​O→CaSO4​⋅2H2​O

Here, plaster of Paris (CaSO4⋅1/2H2O)(CaSO4​⋅1/2H2​O) reacts with water to form gypsum (CaSO4⋅2H2O)(CaSO4​⋅2H2​O).

NCERT Solutions for Class 10 Science Chapter 2 Textbook Chapter End Questions

Question 1: A solution turns red litmus blue; its pH is likely to be (a) 1 (b) 4 (c) 5 (d) 10

Answer: (d) 10

Question 2: 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

Answer: (b) HCl

Question 3: 10 mL of a solution of NaOH is found to be completely neutralized by 8 mL of a given solution of HC1. If we take 20 mL of the same solution of NaOH, the amount of HC1 solution (the same solution as before) required to neutralize it will be (a) 4 mL (b) 8 mL (c) 12 mL (d) 16 mL

Answer: (d) 16 mL

Question 4: Which one of the following types of medicines is used for treating indigestion? (a) Antibiotic (b) Analgesic (c) Antacid (d) Antiseptic

Answer: (c) Antacid

Question 5: Write word equations and then balanced equations for the reaction taking place when (a) dilute sulfuric acid reacts with zinc granules (b) dilute hydrochloric acid reacts with magnesium ribbon (c) dilute sulfuric acid reacts with aluminum powder (d) dilute hydrochloric acid reacts with iron filing

Answer: (a) Zinc+dilute sulfuric acid→Zinc sulfate+HydrogenZinc+dilute sulfuric acid→Zinc sulfate+Hydrogen Zn(�)+H2SO4(��)→ZnSO4(��)+H2(�)Zn(s)+H2​SO4​(aq)→ZnSO4​(aq)+H2​(g)

(b) Magnesium ribbon+dilute hydrochloric acid→Magnesium chloride+HydrogenMagnesium ribbon+dilute hydrochloric acid→Magnesium chloride+Hydrogen Mg(�)+2HCl(��)→MgCl2(��)+H2(�)Mg(s)+2HCl(aq)→MgCl2​(aq)+H2​(g)

(c) Aluminum powder+dilute sulfuric acid→Aluminum sulfate+HydrogenAluminum powder+dilute sulfuric acid→Aluminum sulfate+Hydrogen 2Al(�)+3H2SO4(��)→Al2(SO4)3(��)+3H2(�)2Al(s)+3H2​SO4​(aq)→Al2​(SO4​)3​(aq)+3H2​(g)

(d) Iron filings+dilute hydrochloric acid→Ferric chloride+HydrogenIron filings+dilute hydrochloric acid→Ferric chloride+Hydrogen 2Fe(�)+6HCl(��)→2FeCl3(��)+3H2(�)2Fe(s)+6HCl(aq)→2FeCl3​(aq)+3H2​(g)

Question 6: Compounds such as alcohol and glucose also contain hydrogen but are not categorized as acids. Describe an activity to prove it.

Answer: (i) Take solutions of alcohols and glucose. (ii) Fix two nails on a cork and place the cork in a 100 mL beaker. (iii) Connect the nails to the two terminals of a 6-volt battery through a bulb and a switch. (iv) Pour alcohol in the beaker and switch on the current. (v) The bulb does not glow. (vi) Repeat the experiment with glucose. The bulb does not glow in this case also. (vii) This means no ions or H+ ions are present in the solution. This shows that alcohols and glucose are not acids.

Question 7: Why does distilled water not conduct electricity, whereas rainwater does?

Answer: Distilled water does not conduct electricity because it does not contain any ionic compounds (like acids, bases, or salts) dissolved in it. Rainwater, while falling through the atmosphere, dissolves acidic gas carbon dioxide from the air, forming carbonic acid (H2CO3). Carbonic acid provides hydrogen ions, H+ (aq), and carbonate ions, CO3^2-, to rainwater. Hence, due to the presence of carbonic acid, which provides ions to rainwater, it can conduct electricity.

Question 8: Why do acids not show acidic behavior in the absence of water?

Answer: The acidic behavior of acids is due to the presence of hydrogen ions, �+(��)H+(aq) ions, in them. Acids produce hydrogen ions only in the presence of water. So, in the absence of water, an acid will not form hydrogen ions and hence will not show its acidic behavior.

Question 9: 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.

Answer: (a) D (b) C (c) B (d) A (e) E Increasing order of hydrogen ion concentration: 11 < 9 < 7 < 4 < 1, i.e., C < E < D < A < B

Question 10: 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?

Answer: Fizzing will occur more vigorously in test tube A. Hydrochloric acid (HCl) is a strong acid, whereas acetic acid (CH3COOH) is a weak acid. Being a strong acid, the hydrochloric acid solution contains a much greater amount of hydrogen ions, and thus the fizzing will occur more vigorously in test tube A (containing hydrochloric acid). The fizzing is due to the evolution of hydrogen gas, which is formed by the action of acid on the magnesium metal of the magnesium ribbon.

Question 11: Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.

Answer: The pH of milk falls below 6 as it turns into curd due to the formation of lactic acid during this process. Lactic acid present in it reduces its pH value.

Question 12: 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?

Answer: (a) Milk is made slightly alkaline so that it may not get sour easily due to the formation of lactic acid in it. (b) The alkaline milk takes a longer time to set into curd because the lactic acid being formed has to first neutralize the alkali present in it.

Question 13: Plaster of Paris should be stored in a moisture-proof container. Explain why?

Answer: Plaster of Paris should be stored in a moisture-proof container because the presence of moisture can cause the slow setting of plaster of Paris by bringing about its hydration. This will make the plaster of Paris useless after some time.

Question 14: What is a neutralization reaction? Give two examples.

Answer: The reaction between an acid and a base to form salt and water is called a neutralization reaction. Examples:

Question 15: Give two important uses of washing soda and baking soda.

Answer: Uses of washing soda: (i) Washing soda is used in glass, soap, and paper industries. (ii) It is used for removing the permanent hardness of water.

Uses of baking soda: (i) Baking soda is used as an antacid in medicines to remove the acidity of the stomach. (ii) Baking soda is used for making baking powder (used in making cakes, bread, etc.).

NCERT Solutions for Class 10 Science Chapter 2 (MCQs) [1 Mark each]

1. Which gas is liberated when an acid reacts with a metal?

• (a) Oxygen
• (b) Nitrogen
• (c) Hydrogen
• (d) Carbon dioxide

Answer:

• (c) Hydrogen

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

• (a) Calcium chloride
• (b) Bleaching powder
• (c) Sodium chloride
• (d) Calcium carbonate

Answer:

• (b) Bleaching powder

3. What happens when a solution of sodium hydrogen carbonate is heated?

• (a) It turns red litmus blue
• (b) It decomposes to release carbon dioxide
• (c) It forms a precipitate
• (d) It becomes more acidic

Answer:

• (b) It decomposes to release carbon dioxide

4. Why is it recommended to add acid to water and not water to acid when diluting an acid?

• (a) To avoid an explosion
• (b) To control the temperature rise
• (c) To prevent the formation of poisonous gases
• (d) To minimize the risk of splashing

Answer:

• (d) To minimize the risk of splashing

5. What is the pH of a neutral solution?

• (a) 0
• (b) 7
• (c) 14
• (d) 10

Answer:

• (b) 7

6. Which acid is present in curd and sour substances?

• (a) Hydrochloric acid
• (b) Lactic acid
• (c) Sulfuric acid
• (d) Acetic acid

Answer:

• (b) Lactic acid

7. What is the effect of the concentration of H+ (aq) ions on the nature of the solution?

• (a) It makes the solution basic
• (b) It makes the solution neutral
• (c) It makes the solution more acidic
• (d) It has no effect on the nature of the solution

Answer:

• (c) It makes the solution more acidic

8. What is the role of baking soda in antacids?

• (a) It neutralizes excess stomach acid
• (b) It enhances the flavor of food
• (c) It acts as a preservative
• (d) It increases the shelf life of medicines

Answer:

• (a) It neutralizes excess stomach acid

9. Which of the following substances is not categorized as an acid?

• (a) Vinegar
• (b) Lemon juice
• (c) Glucose
• (d) Hydrochloric acid

Answer:

• (c) Glucose

10. What is the gas evolved when hydrochloric acid reacts with zinc? – (a) Oxygen – (b) Nitrogen – (c) Hydrogen – (d) Carbon dioxide

Answer: – (c) Hydrogen

• CBSE Class 10 Science Chapter-2 Acids, Bases and Salts Notes & NCERT Solution
• CBSE Class 10 Science Chapter-3 Metals and Non-metals Notes & NCERT Solution
• CBSE Class 10 Science Chapter-1 Chemical Reactions and Equations Notes & NCERT Solution
• CBSE Class 10 Science Chapter-4 Carbon and its Compounds Notes & NCERT Solution