Class 10 Science Chapter 2 Acids-Bases and Salts The answer to each chapter is provided in the list so that you can easily browse throughout different chapters NCERT Class 10 Science Chapter 2 Acids-Bases and Salts and select need one.
Class 10 Science Chapter 2 Acids-Bases and Salts
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Additional Questions and Answers
Q.1. What are acids ? How are they produced ?
Ans :- Acids are the chemicals which contain hydrogen atom and are sour in taste.
They are produced when oxides of non-metals react with water.
Q.2. Mention important characteristics of acids.
Ans :- Characteristics of acids :- (i) They are sour in taste.
(ii) They turn blue litmus to red.
(iii) Dilution of acid in water is an exothermic reaction.
(iv) Acids react with metals to evolve hydrogen gas.
(v) Acids reacts with bases to form salt and water.
Q.3. What are bases ? Give the characteristic of bases.
Ans :- Bases are the hydroxide of metals, which give hydroxide ion after dissociation in aqueous solution.
Characteristic of bases –
(i) They are bitter in taste.
(ii) They change red litmus to blue.
(iii) They react with acid to form salt and water.
(iv) Bases are soluble in water and known as alkalies.
Q.4. What is vinegar that is used in the kitchen ?
Ans :- Vinegar is a solution of an acid called acetic acid whose formula is CH₃ COOH.
Q.5. What are indicators ? Give example.
Ans :- The substances, which give different colours with acid and base are called indicator.
For example :- Litmu, Methyl oranges, phenolphthalein.
Q.6. What is lime water ?
Ans :- Dilute alkali solution of water is called as lime water.
Q.7. State differences between acids and bases.
Ans :-
| Acids | Bases |
| (i) Acids are sour to taste. | (i) Bases are bitter to taste. |
| (ii) Acids turns blue litmus to red. | (ii) Bases turns red litmus to blue. |
| (iii) Acid is define as a substance which contains hydrogen ion. | (iii) A base is defined as a substance which contains hydroxyl ion. |
Q.8. Write the name of two natural indicator.
Ans :- (i) Litmus.
(ii) Turmeric.
Q.9. What are ol factory indicators ? Give examples.
Ans :- There are some substances whose odour changes in acidic or basic media. These are called ol factory indicators.
For example :- Vanilla, onion and clove.
Q.10. Is the distilled water acidic/basic/ neutral ? How would you verify it ?
Ans :- The distilled water can be verify with the help of red and blue litmus paper. It shows no reaction in both the litmus paper. So distilled water is neutral.
Q.11. What is an oxide ?
Ans :- An oxide is the compound of an element with oxygen.
Q.12. Name four acids and bases. Write their formula.
Ans :-
| Acids | Formula |
| (i) Hydrochloric acid. | (i) Hcl |
| (ii) Sulphuric acid. | (ii) H₂SO₄ |
| (iii) Acetic acid. | (iii) CH₃ COOH |
| (iv) Nitric acid . | (iv) HNO₃ |
| Bases | Formula |
| (i) Sodium Hydroxide. | (i) NaOH |
| (ii) Calcium Hydroxide. | (ii) Ca(OHH)₂ |
| (iii) Ammonium Hydroxide. | (iii) NH₄OH |
| (iv) Magnesium Hydroxide. | (iv) Mg(OH)₂ |
Q.13. Name the various kind of oxides.
Ans :- Oxides are of three types :-
(i) Acidic oxides.
(ii) Basic oxides.
(iii) Amphoteric oxides.
Q.14. Which gas is used in fire extinguishers ?
Ans :- Carbon dioxide.
Q.15. What is the other name of lime ?
Ans :- Calcium Hydroxide (Ca(OH)₂).
Q.16. Name the acid produce in our stomach.
Ans :- Hydrochloric acid (Hcl).
Q.17. What are antacids. Give one example.
Ans :- During indigestion the stomach produces too much acid and this causes pain and irritation. To get rid of this pain, we use bases called antacids. These antacids neutralise the excess acid.
Example :- Magnesium hydroxide.
Q.18. What is the other name of magnesium hydroxide?
Ans :- Milk of magnesia.
Q.19. Which salt we use in our food ?
Ans :- Sodium chloride. (Nacl)
Q.20. What happens when a base is dissolved in water?
Ans :- When base dissolve in water it generate hydroxide (OH⁻) ions in water.
Q.21. What are alkalis ?
Ans :- Bases which are soluble in water are called alkalis.
Q.22. What do you mean by Pᴴ scale ?
Ans :- A scale for measuring hydrogen ion concentration ina solution called Pᴴ scale. The h in Pᴴ stands for “potenz” in German, meaning powder. On the Pᴴ scale we can measure Pᴴ generally from 0 to 14. Pᴴ should be thought of simply as a number which indicates the acidic or basic nature of a solution. Higher the hydronium ion concentration, lower is he Pᴴ value.
Q.23. What are the Pᴴ value of a neutral, a acidic and a basic solution.
Ans :- Pᴴ value of a neutral solution is 7.
Pᴴ value of a acidic solution is less than 7.
Pᴴ value of basic solution is more than 7.
Q.24. What is the Pᴴ range of our body ?
Ans :- 7.0 to 7.8.
Q.25. What is acid rain ? What is it’s effect ?
Ans :- When Pᴴ of rain water is less than 5.6 it is called acid rain. When acid rain flows into the rivers, it lowers the Pᴴ of the river water. The survival of aquatic life in such rivers becomes difficult.
Q.26. Does acid solution conduct electricity ?
Ans :- Yes, all acid solution conduct electricity. They allow the passage of an electric current through them.
Q.27. Distinguish between acid and alkali.
Ans :-
| Acid | Alkali |
| 1. The compound formed by the reaction of acidic oxide with water is called acid. | 1. The hydroxide of metals which dissolve in water are known as alkali. |
| 2. For example :- Hcl, HNO₃ H₂SO₄ | 2. For example :- NaOH, KOH, NH₄ OH. |
Q.28. How do you measure the strength of an acid or a base ?
Ans :- The strength of an acid or a base depends on the number of H⁺ ions or OH⁻ ions produced respectively by its given amount. If we take one molar concentration of hydrochloric acid and acetic acid then the acid which gives rise to move of H⁺ ions is a stronger acid and the one that gives less H⁺ ions is a weaken acid. In this case, it is found that hydrochloric acid is a strong acid. Similarly one can find whether it is a strong base or a weak base.
Q.29. Choose strong acid and strong base from the following- CH₃ COOH, NH₄ OH, KOH, Hcl
Ans :- Strong acid :- HCI
Strong base :- KOH
Q.30. (i) An aqueous solution has a Pᴴ value of 7.0. Is this solution acidic, basic or neutral ?
(ii) Which has a higher Pᴴ value; 1 M Hcl or I M NaOH ?
Ans :- (i) Neutral.
(ii) IM NAOH has higher Pᴴ value.
Q.31. Given below are the Pᴴ values of four different liquids. 7.0, 14.0, 4.0, 2.0 Which of these could be that of
(i) Lemon Juice.
(ii) Distilled water.
(iii) IM NaOH.
(iv) Tomato Juice.
Ans :- (i) Lemon juice 2.0
(ii) Tomato juice 4.0
(iii) Distilled water 7.0
(iv) IMNaOH 14.0
Q.32. What is the importance of Pᴴ in tooth decay ?
Ans :- Tooth decay starts when the Pᴴ of the mouth is lower than 5.5. Tooth enamel made of calcium phosphate is the hardest substance in the body. It does not dissolve in water, but in corroded when the Pᴴ in the mouth is below 5.5. Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating. The best way to prevent this is to clean the mouth after eating food. Using tooth pastes, which are generally basic, for cleaning the teeth can neutralise the excess acid and prevent tooth decay.
Q.33. Name the acids found in the following :- vinegar, Ant’s sting, curd, orange, unripe mangoes.
Ans :- Vinegar – Acetic acid.
Ant’s sting – Formic acid
Orange – Citric acid
Curd – Lactic acid
Unripe mangoes – Tartaric acid
Q.34. Name the base found in the following :- Lime water, Soap, Milk of magnesia
Ans :- Lime water – Calcium hydroxide.
Soap – Sodium hydroxide/potassium hydroxide.
Milk of magnesia – Magnesium hydroxide.
Q.35. Out of tap water and pure water which is a poor q conductor ?
Ans :- Tap water is a very poor conductor while pure water or distilled water is non conductor.
Q.36. Match the items given in column I with those given in column II.
| Column I | Column II |
| (a) Vinegar. | (i) Changes red litmus blue |
| (b) Sodium Chloride. | (ii) is sour in taste. |
| (c) Milk of magnesia. | (iii) major salt in sea. |
| (d) Potassium nitrate. | (iv) used in fertilizer industry. |
Ans :- (a) Vinegar – (ii) is sour in taste.
(b) Sodium chloride – (iii) major salt in sea.
(c) Milk of magnesia – (i) changes red litmus blue
(d) Potassium nitrate – (iv) used in fertilizer industry.
Q.37. What is the chlor-alkali process ? Why it is called chlor-alkali process ?
Ans :- When electricity is passed through an aqueous solution of sodium chloride, it decomposes to form sodium hydroxide. The process is called the chlor-alkali process. It is called chlor-alkali process because of the products formed cholar for chlorine and alkali for sodium hydroxide.
2Nacl(aq) + 2H₂O (l) → 2NaOH (aq) + Cl₂ (g) + H₂ (g)
Q.38. Write two uses of bleaching powder.
Ans :- (i) As an oxidising agent in many chemical industries.
(ii) for disinfecting drinking water to make it free of germs.
Q.39. Among the following salts, which salts are acidic, basic or neutral ? Sodium chloride, potassium nitrate, aluminium chloride, zinc sulphate, sodium acetate, sodium carbonate, copper sulphate, sodium sulphate, ammonium chloride.
Ans :- Acidic salts :- Aluminium chloride, zinc sulphate, copper sulphate, ammonium sulphate.
Basic salts :- Sodium acetate, sodium carbonate.
Neutral salts :- Sodium chloride, potassium nitrate, sodium sulphate.
Q.40. Write the chemical formula of washing soda. How can it be obtained form baking soda ? Describe the household application of washing soda.
Ans :- (i) Washing soda is sodium carbonate, Na₂ CO₃ IOH₂O
(ii) Baking soda on heating gives sodium carbonate.
(iii) It is used as cleansing agent.
Multiple choice questions
Q.1. Which one of the following types of medicine is used for treating indigestion ?
(a) Antibiotic.
(b) Analgesic.
(c) Antacid.
(d) Antiseptic.
Ans :- (c) Antacid.
Q.2. The solution of sodium hydroxide is
(a) Acidic.
(b) Alkaline.
(c) Neutrall.
(d) Amphoteric.
Ans :- (b) Alkaline.
Q.3. Name the acid present in lemon juice.
(a) Acetic acid.
(b) Citric acid.
(c) Propanoic acid.
(d) Sodium carbonate.
Ans. (b) Citric acid.
Q.4. Out of these which one gas is used in fire extinguishers.
(a) CO₂
(b) SO₂
(c) NO₂
(d) H₂S
Ans :- (a) CO₂
Q.5. Milk of magnesia has
(a) Acidic nature.
(b) Basic nature.
(c) Amphoteric nature.
(d) Neutral.
Ans :- (a) Acidic nature.
Q.6. Which of the following will give Pᴴ less than seven?
(a) Blood.
(b) Milk of magnesia.
(c) Sodium hydroxide.
(d) Gastric juice.
Ans :- (d) Gastric juice.
Q.7. Which of the following compounds is used to repair fractured bones ?
(a) Na₂CO₃
(b) CaOcl₂
(c) CaSo₄½ H₂O
(d) CaSo₄.5H₂O
Ans :- (c) CaSo₄½ H₂O
Q.8. Tooth enamel contains.
(a) Calcium carbonate.
(b) Calcium sulphate.
(c) Calcium chloride.
(d) Calcium phosphate.
Ans :- (d) Calcium phosphate.
Q.9. The natural indicator among the following is
(a) phenolph thalein.
(b) methyl orange.
(c) methyl red.
(d) litmus.
Ans :- (d) litmus.
Q.10. Basic solutions contain :
(a) H⁺ ions.
(b) OH⁻ ions.
(c) Both H⁺ and OH⁻ ions.
(d) Na⁺ ions.
Ans :- (c) Both H⁺ and OH⁻ ions.
Q.11. What is corrosion ?
Ans :- The process that takes place when metals and alloys are chemically attached by oxygen, water or acid in their immediate environment is known as corrosion. It is a slow process.
Q.12. What is the other name of calcium hydroxide ?
Ans :- Slaked lime.
Q.13. What is rock salt ? Give example.
Ans :- Some of salts are mined from the minerals, that are called as rock salt.
Example :- Common salt (Nacl)
Q.14. Name two naturally occurring acids.
Ans :- Citric acid and acetic acid.
Q.15. Name a hydrogen containing compound which does not act as an acid.
Ans :- Methane (CH₄)
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