Ch 2 Acids, Bases and Salts Class 10 Important Questions | NCERT Science Chapter-2

Ch 2 Acids, Bases and Salts Class 10 Important Questions

The start of class 10 marks the beginning of the foundation for class 11 and class 12. It is very important study the basics in order to understand each and every chapter properly. In this page, we have provided all the important question for cbse class 9 that could be asked in the examination. Students also need to study the ncert solutions for class 10 in order to gain more knowledge and understanding the lessons. Questions and Answers are way to learn the new things in a proper way. NCERT textbooks downloads for class 9 in pdf are also available for the students if they need more help. By downloading these books, they can study from it. Our experts also prepared revision notes for class 9 so that students should see the details of each and every chapters. Class 9 important questions are the best to revise all the chapters in the best way.

Short Answer Questions-I (SAQs-I): 2 Marks
Q1. Classify the following into acidic oxides anc basic oxides : Na₂O, SO₂, MgO, CO₂

AnswerAcidic oxides — SO₂, CO₂Basic oxides — Na₂O, MgO₂

Q2. What is the change in pH values of milk when it changes into curd? Explain. 

Answer

pH decrease by the presence of lactic acid in curd because acids generally have a low pH value. Hence, pH will decrease when milk changes into curd. 

Q3.What is cause of decay of tooth? What is the pH of mouth required.

Answer

The enamel of our tooth started getting damaged when pH of tooth is less than 5.5. Tooth decay starts when the pH of the mouth is lower than 5.5 . Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating.  Toothpaste is basic in nature is used to neutralize the acid.

Q4. A white powder is added while baking breads and cakes to make them soft and fluffy. What is the name of the powder? What are the main ingredients in it? What are the functions of each ingredient? AnswerBaking powder.Baking soda and an edible acid like tartaric acid. Baking soda (NaHCO₃) is used to release CO₂ gas when heated. Tartaric acid is used to avoid the bitter taste by reacting with the Na₂CO₃ formed.

Short Answer Questions-II (SAQs-II): 3 Marks

Q1. (a) What is the action of litmus on: (i) dry ammonia gas(ii) solution of ammonia gas in water (b) State the observations you would make on adding sodium hydroxide to aqueous solution of (i) ferrous sulphate(ii) aluminium chloride. Give balanced chemical equations.

Answer(a)

(i) No change in colour (ii) Red litmus turns blue 

(b)

(i) 2NaOH(aq) + FeSO₄(aq) → Fe(OH)₂(s) + Na₂SO₄(aq) Sodium hydroxide + Ferrous sulphate → Ferrous hydroxide + Sodium Sulphate 

(ii) 3NaOH(aq) + AlCl₃(aq) → Al(OH)₃(s) + NaCl(aq)Sodium hydroxide + Aluminium chloride → Aluminium hydroxide + Sodium chloride 

Q2. Name the three products of ‘chlor-alkali process. Write one commercially or industrially important material each that can be prepared from each of these products.

 AnswerThe three products are: Sodium hydroxide (NaOH), Chlorine (Cl₂) and Hydrogen (H₂).NaOH: used in making soaps and detergents and also in paper making or artificial fibres.Cl₂: PVC, pesticides, CFCs.H₂: fuels, margarine, NH₃ for fertilizers. 

Q3. Draw a neat and labelled diagram to show the following activity: Action of dilute sulphuric acid on zinc granules(i) Name the gas evolved. (ii) How will you test for the gas. 
Answer

(i) The gas evolved is hydrogen. (ii) Zn(s) + H₂SO₄(aq) → ZnSO₄(aq) + H₂(g) Test for H₂ gas: The presence of H₂ gas can be tested by passing the gas through soap solution and then bringing a burning splinter near the soap bubbles filled with the gas. If the gas burns with a pop sound, it is hydrogen. 

Long Answer Questions (LAQs): 5 Marks

1. (i) Explain why is hydrochloric acid a strong acid and acetic acid, a weak acid. How can it be verified? (ii) Explain why aqueous solution of an acid conducts electricity. (iii) You have four solutions A, B, C and D. The pH of solution A is 6, B is 9, C is 12 and D is 7.(a) Identify the most acidic and most basic solutions.(b) Arrange the above four solutions in the increasing order of H+ ion concentration. (c) State the change in colour of pH paper on dipping in solution C and D. 
Answer
(i) HCI will give rise to more H⁺ ions and CH₃COOH produces less H⁺ ions on dissociation. The colour of pH paper depends on the concentration of H⁺ ion. Colour becomes red for high H⁺ concentration.(ii) Aqueous solution of acids have H⁺ which carry electric current through the solution.(iii) (a) Most acidic: A and Most basic: C(b) C, B, D, A/C < B < D < A(c) In C: blue, In D: green

2. Give suitable reasons for the following statements: (i) Rain water conducts electricity but distilled water does not.(ii) We feel burning sensation in the stomach when we over eat.(iii) A tarnished copper vessel regains its shine when rubbed with lemon.(iv) The crystals of washing soda change to white powder on exposure to air. (v) An aqueous solution of sodium chloride is neutral but an aqueous solution of sodium carbonate is basic. 
Answer
(i) Distilled water is a pure form of water, is neither acidic nor basic in nature. So distilled water does not dissociate into ions, since, conduction of electricity requires free ions so, distilled water does not conduct electricity. While rain water being an impure form of water, contains many ionic species. These ions are responsible for electrical conductivity of rain water.(ii) Because when we over eat too much HCI is produced in our stomach which causes burning sensation.(iii) Copper vessels tarnish is due to the formation of basic copper carbonate [Cu₂(OH)₂CO₃] which gets neutralized when rubbed with lemon and the copper vessel regains its shine.(iv) Washing soda (sodium carbonate decahydrate), Na₂CO₃.10H₂O when exposed to air, it loses 10 molecules of water and changes to white powder.(v) Sodium chloride is a salt of strong acid HCI and strong base NaOH, so it is neutral. Sodium carbonate is a salt of weak acid H₂CO₃ and strong base NaOH, so it is basic. NaCI + H₂O → NaOH + HCI Na₂CO₃ + H₂O → NaOH + H₂CO₃

Important Links

NCERT Quick Revision Notes- Ch 2 Acids, Bases and Salts

NCERT Solution- Ch 2 Acids, Bases and Salts 

Important MCQs- Ch 2 Acids, Bases and Salts

For Free, Video Lectures Click here