Introduction:
NCERT Solutions for Class 10 Science Chapter 2 “Acids, Bases and Salts” (Intext Questions and Answers) provide clear and accurate answers to all the intext questions given in the NCERT textbook. This chapter helps students understand the properties of acids, bases, and salts, their reactions, the pH scale, indicators, and their importance in everyday life.
These solutions are prepared in simple language according to the latest CBSE syllabus, making it easier for students to learn concepts, complete homework, and prepare for examinations. By practicing these answers, students can strengthen their understanding of chemical reactions involving acids, bases, and salts and improve their problem-solving skills.
All answers are presented in a step-by-step manner and follow NCERT guidelines, ensuring better conceptual clarity and effective exam preparation.
CH-2 Acids , Bases and Salts
INTEXT QUESTIONS
Page 18
Ques 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) First dip the red litmus paper in each of the three test tubes.
• The tube in which it turns blue will indicate the basic solution.
(ii) Now dip this blue litmus paper formed in (i) in the remaining two test tubes.
• The tube in which it again changes back to red indicates the acidic solution.
(iii) The remaining tube in which neither red litmus turns blue nor blue litmus turns red contains the distilled water.
Page 22
Ques 1:- Why should curd and sour substances not be kept in brass and copper vessels?
Ans:- Both curd and sour substances contain some acids in them. They react with copper or brass vessels to form certain salts which are of Poisonous nature. Therefore, it is not advisable to keep them in these containers.
Ques 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?
Ans:- When a metal reacts with an acid, hydrogen gas (H2) is usually liberated.
Example:- When zinc reacts with dilute sulphuric acid, hydrogen gas is produced.
Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)
Test for Hydrogen Gas:- The hydrogen gas evolved can be tested by bringing a burning candle or matchstick near the mouth of the test tube. Hydrogen burns with a characteristic "pop" sound, confirming its presence.
Ques 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.
Ans:- The gas evolved extinguishes a burning candle, so it is carbon dioxide (CO₂). Since one of the products formed is calcium chloride (CaCl₂), the metal compound A must be calcium carbonate (CaCO₃).
The balanced chemical equation is:
CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)
Concept:- Metal carbonates react with dilute acids to produce a salt, carbon dioxide gas, and water.
Page 25
Ques 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?
Ans:- Acids such as HCl and HNO₃ ionize in aqueous solution to produce hydrogen ions (H⁺). Therefore, they show acidic character in water.
On the other hand, compounds like glucose (C₆H₁₂O₆) and ethanol (C₂H₅OH) do not ionize in aqueous solution to produce H⁺ ions.
Hence, they do not show acidic character.
Conclusion: The acidic character of a substance is due to the presence of H⁺ ions in aqueous solution.
Ques 2:- Why does the aqueous solution of an acid conduct electricity?
Ans:- An aqueous solution of an acid (HA) dissociates in water to produce H⁺ ions and anions (A⁻). These ions are free to move in the solution and carry electric charge. Therefore, the aqueous solution of an acid conducts electricity.
OR
Acids in aqueous solution release H⁺ ions and anions (A⁻). Since ions are the carriers of electric current, the aqueous solution of an acid conducts electricity.
Ques 3:- Why does dry HCl gas not change the colour of the dry litmus paper?
Ans:- Dry HCl gas does not change the colour of dry litmus paper because it does not produce H⁺ ions in the absence of water. Since dry litmus paper contains no moisture, HCl cannot ionize to form H⁺ ions. Therefore, dry HCl gas does not change the colour of dry litmus paper.
Ques 4:- While diluting an acid. why is it recommended that the acid should be added to water and not water to the acid?
Ans:- Dilution of a concentrated acid with water is a highly exothermic process. If water is added to the acid, a large amount of heat is generated suddenly, which may cause the acid to splash out and can even break the beaker due to excessive heating. Therefore, acid should always be added slowly to water while stirring continuously.
Ques 5:- How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?
Ans:- When an acid solution is diluted by adding water, the concentration of hydronium ions (H₃O⁺)per unit volume decreases because the same number of ions are dispersed in a larger volume of water. Therefore, the acidic strength of the solution decreases.
shorter version:Ans:- When a solution of an acid is diluted, the concentration of hydronium ions (H₃O⁺) per unit volume decreases due to the addition of water.
Ques 6:- How is concentration of hydroxide ions (OH-) affected when excess base is dissolved in a solution of sodium hydroxide?
Ans:- On dissolving excess base in a solution of sodium hydroxide, the concentration of hydroxide ions (OH⁻) per unit volume increases. Therefore, the solution becomes more basic (alkaline).
Ques 1:- You have two solutions A and B. The pH of the solution A is 6 and pH or solution B is 8.Which solution has more hydrogen ion concentration? Which of these is acidic and which one is basic?
Ans:- The pH of a solution is inversely proportional to its hydrogen ion (H⁺) concentration. Therefore, the solution having a lower
pH has a higher hydrogen ion concentration. Since solution A has a pH of 6 and solution B has a pH of 8,
solution A has more hydrogen ion concentration.
A solution with pH less than 7 is acidic. Therefore, solution A is acidic.
A solution with pH greater than 7 is basic. Therefore, solution B is basic.
Ques 2:- What effect does the concentration Of H+ (aq) ions have on the acidic nature of the solution?
Ans:- The acidic nature of a solution depends on the concentration of H⁺(aq) ions present in it. As the concentration of H⁺ ions increases, the acidity of the solution also increases. Therefore, a solution with a higher concentration of H⁺ ions is more acidic.
Ques 3:- Do basic solutions also have H+ (aq) ions? If yes, then why are these solutions basic?
Ans:- Yes, basic solutions also contain H⁺(aq) ions. However, they are basic because the concentration of OH⁻(aq) ions is greater than the concentration of H⁺(aq) ions in the solution.
Ques 4:- Under what soil condition do you think a farmer would treat the soil of his field with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate)?
Ans:- Most plants grow best when the pH of the soil is close to 7. If the soil becomes too acidic, plant growth is adversely affected. Since quick lime (CaO), slaked lime [Ca(OH)₂], and chalk (CaCO₃) are basic substances, a farmer adds them to the soil to neutralize its acidity. Therefore, these substances are used when the soil is highly acidic.
Page 33
Ques 1:- What is the common name of the compound CaOCl₂?
Ans:- The common name of the compound CaOCl₂ is bleaching powder.
Ques 2:- Name the substance which on treatment with chlorine yields bleaching powder.
Ans:- Dry slaked lime [Ca(OH)₂] on treatment with chlorine yields bleaching powder.
Ques 3:- Name the sodium compound which is used for softening hard water.
Ans:- Washing soda (sodium carbonate, Na₂CO₃·10H₂O) is used for softening hard water.
Ques 4:- What will happen if a solution of sodium hydrogen carbonate is heated? Give the equation of the reaction involved
Ans:- On heating, sodium hydrogen carbonate decomposes to form sodium carbonate, carbon dioxide, and water.
2NaHCO3 → Na2CO3 + CO2 + H2O
NaHCO3 = Sodium hydrogen carbonate
Na2CO3 = Sodium carbonate
CO2 = Carbon dioxide
H2O = Water
Ques 5:- Write an equation to show the reaction between plaster of Paris and water.
Ans:- Plaster of Paris reacts with water to form gypsum.
CaSO4·½H2O + 1½H2O → CaSO4·2H2O
Plaster of Paris + Water → Gypsum
Conclusion
NCERT Solutions for Class 10 Science Chapter 2 – Acids, Bases and Salts (Intext Questions and Answers) help students understand important concepts in a simple and effective manner. These solutions provide accurate answers based on the latest NCERT textbook and CBSE syllabus, making them useful for homework, revision, and exam preparation.
Regular practice of these intext questions will strengthen conceptual understanding, improve problem-solving skills, and boost confidence in Science. Students are encouraged to go through each answer carefully to achieve better academic performance and build a strong foundation in Chemistry.
Frequently Asked Questions (FAQs)
Q1. What are acids, bases, and salts?
Acids are substances that release hydrogen ions (H⁺) in water, bases release hydroxide ions (OH⁻), and salts are formed when an acid reacts with a base.
Q2. Why are NCERT Solutions important for Class 10 Science Chapter 2?
NCERT Solutions help students understand concepts clearly, complete assignments, and prepare effectively for CBSE board examinations.
Q3. What is the pH scale?
The pH scale is used to measure the acidity or basicity of a solution. It ranges from 0 to 14, where 7 is neutral, values below 7 are acidic, and values above 7 are basic.
Q4. Which topics are covered in Chapter 2: Acids, Bases and Salts?
The chapter covers acids and bases, indicators, chemical properties, pH scale, salts, bleaching powder, baking soda, washing soda, and plaster of Paris.
Q5. Are these NCERT Solutions sufficient for board exam preparation?
Yes, NCERT Solutions are essential for board exam preparation as many questions are directly or indirectly based on NCERT concepts and exercises.
){kind=link}
0 Comments
Please do not enter any spam link in the comment box.