NCERT Exemplar Solutions for Class 10 Science Chapter 2 Acids, Bases and Salts (MCQ, SAQ and LAQ)
Chapter Name | NCERT Exemplar Solutions for Class 9 Science Ch 2 Acids, Bases and Salts |
Topics Covered |
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Related Study |
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Objective Type Questions for Acids, Bases and Salts
1. What happens when a solution of an acid is mixed with a solution of a base in a test tube?
(i) The temperature of the solution increases
(ii) The temperature of the solution decreases
(iii) The temperature of the solution remains the same
(iv) Salt formation takes place
(a) (i) only
(b)
(i) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)
Solution
(d) (i) and (iv)
When acid is mixed with a solution of base it results in neutralization reaction. Neutralization is an exothermic reaction which result in the formation salt.
2. An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution
would reverse the change?
(a) Baking powder
(b) Lime
(c) Ammonium hydroxide solution
(d) Hydrochloric acid
Solution
(d) Hydrochloric acid
If the solution turns red litmus to blue color then the solution should be basic in nature. Its effect can be neutralized by adding an acid hence, (d) Hydrochloric acid is the answer.
3. During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the
guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to
(a) absorb the evolved gas
(b) moisten the gas
(c) absorb moisture from the gas
(d) absorb Cl– ions from the evolved gas
Solution
(c) absorb moisture from the gas
Calcium is a good dehydrating agent. It has property to absorb moisture. Hence it is used as a desiccant to dry gases and Hydrocarbons in the industries.
4. Which of the following salts does not contain water of crystallisation ?
(a) Blue vitriol
(b) Baking soda
(c) Washing soda
(d) Gypsum
Solution
(b) Baking soda
Baking sodas is white amorphous powder where as other salts given in the question are crystalline in nature.
5. Sodium carbonate is a basic salt because it is a salt of
(a) strong acid and strong base
(b) weak acid and weak base
(c) strong acid and weak base
(d) weak acid and strong base
Solution
(d) weak acid and strong base
Salt formed by weak acid and strong base form strong salt. Here Sodium is a strong base and carbonate is a weak acid.
6. Calcium phosphate is present in tooth enamel. Its nature is
(a) basic
(b) acidic
(c) neutral
(d) amphoteric
Solution
(a) basic
Phosphate ion present in calcium phosphate is a strong base and it form a strong salt. Hence calcium Phosphate is basic in nature.
7. A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH
paper yellowish - orange. Which of the following would change the colour of this pH paper to greenish-blue?
(a) Lemon juice
(b) Vinegar
(c) Common salt
(d) An antacid
Solution
(d) An antacid
Sample solution turn pH paper yellowish - orange which confirm the acidic nature of the sample. In order to make the color to greenish - blue we have to add an antacid.
8. Which of the following gives the correct increasing order of acidic strength
(a) Water < Acetic acid < Hydrochloric acid
(b) Water < Hydrochloric acid< Acetic acid
(c) Acetic acid< Water < Hydrochloric acid
(d) Hydrochloric acid< Water<Acetic acid
Solution
(a) Water < Acetic acid < Hydrochloric acid
Water is neutral in its pure form, Acetic acid is an organic acid which is weak in nature and hydrochloric acid is a strong acid.
9. If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done?
(a) Wash the hand with saline solution
(b) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate
(c) After washing with plenty of water apply solution of sodium hydroxide on the hand
(d) Neutralise the acid with a strong alkali
Solution
(b) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate .
Washing affected hand with plenty of water will reduce the concentration of the acid. Remaining traces of the acid can be neutralized by applying a paste of Hydrogen carbonate which is basic in nature. Though NaOH is also a base but it is corrosive in nature hence it is not used to neutralize the acid.
10. Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements
are true about the gas evolved?
(i) It turns lime water milky
(ii) It extinguishes a burning splinter
(iii) It dissolves in a solution of sodium hydroxide
(iv) It has a pungent odour
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (ii), (iii) and (iv)
(d) (i) and (iv)
Solution
(a) (i) and (ii)
Reaction between Sodium hydrogen carbonate and acetic acid lead to evolution of carbon-di-oxide gas. CO2 turns the lime water milky and extinguish a burning splinter.
11. 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
(a) (i) and (ii)
(b) (i), (ii) and (iv)
(c) (i) and (iii)
(d) (i), (iii) and (iv)
Solution
(a) (i) and (ii)
12. One of the constituents of baking powder is sodium hydrogen carbonate, the other constituent is
(a) hydrochloric acid
(b) tartaric acid
(c) acetic acid
(d) sulphuric acid
Solution
(b) tartaric acid
A Mild edible acid along with Sodium Hydrogen Carbonate is used to prepare baking powder. Here acetic acid or citric acid can also be used in place of tartaric acid.
13. To protect tooth decay we are advised to brush our teeth regularly. The nature of the tooth paste
commonly used is
(a) acidic
(b) neutral
(c) basic
(d) corrosive
Solution
(c) Basic
Teeth will be acidic in nature because of bacterial activity in mouth. To neutralize the acid toothpaste will be neutral in nature.
14. Which of the following statements is correct about an aqueous solution of an acid and of a base?
(i) Higher the pH, stronger the acid
(ii) Higher the pH, weaker the acid
(iii) Lower the pH, stronger the base
(iv) Lower the pH, weaker the base
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)
Solution
(d) (ii) and (iv)
On a PH scale acids are those whose pH is below 7 lower is the PH stronger will be acid and similarly Bases are those whose pH is more than 7. Higher is the PH strong will be acid.
15. The pH of the gastric juices released during digestion is
(a) less than 7
(b) more than 7
(c) equal to 7
(d) equal to 0
Solution
(a) less than 7
The PH is acidic to below 7 to ensure easy breakdown of food particles. PH of stomach juices is usually 3.
16. Which of the following phenomena occur, when a small amount of acid is added to water?
(i) Ionisation
(ii) Neutralisation
(iii) Dilution
(iv) Salt formation
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (ii) and (iv)
Solution
(b) (i) and (iii)
17. Which one of the following can be used as an acid–base indicator by a visually impared student?
(a) Litmus
(b) Turmeric
(c) Vanilla essence
(d) Petunia leaves
Solution
(c) Vanilla essence
Vanilla essence can be used as an olfactory indicator hence it can be used as acid base indicator by visually impaired students.
18. Which of the following substance will not give carbon dioxide on treatment with dilute acid?
(a) Marble
(b) Limestone
(c) Baking soda
(d) Lime
Solution
(d) Lime
Marble, Limestone and baking soda have carbonates which produces CO2 gas. Lime contains Hydroxide which will not produce CO2.
19. Which of the following is acidic in nature?
(a) Lime juice
(b) Human blood
(c) Lime water
(d) Antacid
Solution
(a) Lime juice
Lime juice has citric acid in it. Hence it is acidic in nature.
20. In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus
(Figure 2.1) was set up. Which among the following statement(s) is(are) correct?
(i) Bulb will not glow because electrolyte is not acidic
(ii) Bulb will glow because NaOH is a strong base and furnishes ions for conduction.
(iii) Bulb will not glow because circuit is incomplete
(iv) Bulb will not glow because it depends upon the type of electrolytic solution
(a) (i) and (iii)
(b) (ii) and (iv)
(c) (ii) only
(d) (iv) only
(c) (ii) only
(a) Hydrochloric acid
(b) Sulphuric acid
(c) Nitric acid
(d) Aqua regia
(a) Hydrochloric acid
(b) Citric acid
(c) Sulphuric acid
(d) Nitric acid
(b) Citric acid
(a) NaOH
(b) KOH
(c) NH4OH
(d) C2H5OH
Solution
(d) C2H5OH
C2H5OH is an alcohol not a base.
24. Which of the following statements is not correct?
(a) All metal carbonates react with acid to give a salt, water and carbon dioxide
(b) All metal oxides react with water to give salt and acid
(c) Some metals react with acids to give salt and hydrogen
(d) Some non metal oxides react with water to form an acid
Solution
(b) All metal oxides react with water to give salt and acid
Metal oxides are basic in nature hence they give alkaline solution when dissolved in water.
25. Match the chemical substances given in Column (A) with their appropriate application given in Column
(B)
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Column (A) |
Column (B) |
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(A) Bleaching powder |
(i) Preparation of glass |
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(B) Baking soda |
(ii) Production of H2 and Cl2 |
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(C) Washing soda |
(iii) Decolourisation |
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(D) Sodium chloride |
(iv) Antacid |
(a) A—(ii), B—(i), C—(iv), D—(iii)
(b) A—(iii), B—(ii), C—(iv), D—(i)
(c) A—(iii), B—(iv), C—(i), D—(ii)
(d) A—(ii), B—(iv), C—(i), D—(iii)
Solution
(c) A—(iii), B—(iv), C—(i), D—(ii)
26. Equal volumes of hydrochloric acid and sodium hydroxide
solutions of same concentration are mixed and the pH of the
resulting solution is checked with a pH paper. What would be the
colour obtained? (You may use colour guide given in Figure 2.2
(b) Yellow
(c) Yellowish green
(d) Blue
(c) Yellowish green
(i) It does not ionise in the solution as it is a covalent compound.
(ii) It ionises in the solution
(iii) It gives both hydrogen and hydroxyl ion in the solution
(iv) It forms hydronium ion in the solution due to the combination of hydrogen ion with water molecule
(b) (iii) only
(c) (ii) and (iv)
(d) (iii) and (iv)
(c) (ii) and (iv)
(a) Bitter and change red litmus to blue
(b) Sour and change red litmus to blue
(c) Sour and change blue litmus to red
(d) Bitter and change blue litmus to red
(c) Sour and change blue litmus to red
(a) H3O+ + Cl-
(b) H3O+ + OH-
(c) Cl- + OH-
(d) unionised HCl
(a) H3O+ + Cl-
(a) 2NaCl(l) + 2H2O(l) → 2NaOH(l) + Cl2(g) + H2(g)
(b) 2NaCl(aq) + 2H2O(aq) → 2NaOH(aq) + Cl2(g) + H2(g)
(c) 2NaCl(aq) + 2H2O(l) → 2NaOH(aq) + Cl2(aq) + H2(aq)
(d) 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + Cl2(g) + H2(g)
Short Answer Questions for Acids, Bases and Salts
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Column (A) |
Column (B) |
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(a) Lactic acid |
(i) Tomato |
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(b) Acetic acid |
(ii) Lemon |
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(c) Citric acid |
(iii) Vinegar |
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(d) Oxalic acid |
(iv) Curd |
Column (A) | Column (B) |
(a) Lactic acid | (i) Tomato |
(b) Acetic acid | (ii) Lemon |
(c) Citric acid | (iii) Vinegar |
(d) Oxalic acid | (iv) Curd |
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Column (A) |
Column (B) |
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(a) Plaster of Paris |
(i) Ca(OH)2 |
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(b) Gypsum |
(ii) CaSO4. ½ H2O |
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(c) Bleaching Powder |
(iii) CaSO4. 2H2O |
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(d) Slaked Lime |
(iv) CaOCl2 |
Column (A) | Column (B) |
(a) Plaster of Paris | (ii) CaSO4. ½ H2O |
(b) Gypsum | (iii) CaSO4. 2H2O |
(c) Bleaching Powder | (iv) CaOCl2 |
(d) Slaked Lime | (i) Ca(OH)2 |
- Dry HCl gas - No effect
- Moistened NH3 gas - Turns litmus paper to blue colour
- Lemon juice - Turns litmus paper to red colour
- Carbonated soft drink - Turns litmus paper to blue colour
- Curd - Turns litmus paper to red colour
- Soap solution - Turns litmus paper to blue colour
Ant sting release methanoic acid. Chemical formula of methanoic acid is HCOOH. If we rub baking soda on the affected area it can give relief from the discomfort caused by ant sting.
Nitric acid dissolved egg shell which is made up of Calcium carbonate. Calcium carbonate on reacting with nitric acid yield Calcium Nitrate and carbon-di-oxide gas.
Student can use Phenopthalein indicator to check the nature of the solution.
When we heat baking powder CO2 is released which can be confirmed by passing evolved gas into lime water which will turn milky. This reaction will not happen when you heat washing soda.
Salt A is Baking soda (Sodium Hydrogen Carbonate) which will turn to Sodium carbonate( Salt B) on heating. Gas C turn lime water milky hence it must be CO2.
X: Chlorine (Cl2)
Y: Bleaching powder (CaOCl2)
Ca(OH)2(s) + Cl2(g) → CaOCl2 (s) + H2O
CaOCl2:Calcium oxychloride (bleaching powder)
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Salted Obtained from |
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Name of the Salt |
Formula |
Base |
Acid |
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Ammonium chloride |
NH4Cl |
NH4OH |
--- |
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Copper sulphate |
-- |
-- |
H2SO4 |
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Sodium chloride |
NaCl |
NaOH |
---- |
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Magnesium nitrate |
Mg(NO3)2 |
--- |
HNO3 |
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Potassium sulphate |
K2SO4 |
-- |
-- |
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Calcium nitrate |
Ca(NO3)2 |
Ca(OH)2 |
-- |
Salted Obtained from | |||
Name of the Salt | Formula | Base | Acid |
Ammonium chloride | NH4Cl | NH4OH | HCl |
Copper sulphate | CuSO4 | Cu(OH)2 | H2SO4 |
Sodium chloride | NaCl | NaOH | HCl |
Magnesium nitrate | Mg(NO3)2 | Mg(OH)2 | HNO3 |
Potassium sulphate | K2SO4 | KOH | H2SO4 |
Calcium nitrate | Ca(NO3)2 | Ca(OH)2 | HNO3 |
Strong acids are those which gets completely ionized and weak acids are those which gets partially ionized.
- Hydrochloric acid- Strong Acid
- citric acid- Weak Acid
- acetic acid- Weak Acid
- nitric acid, - Strong Acid
- formic acid- Weak Acid
- sulphuric acid- Strong Acid
When Zinc reacts with Dilute acid solution, following reaction takes place Hydrogen gas is evolved
Zn + 2HCl → ZnCl2 + H2
When Hydrogen gas is brought near Burning flame, pop pops up which is the confirmation for evolution of Hydrogen gas.
Long Answer questions for Acids, Bases and Salts
(a) In place of zinc granules, same amount of zinc dust is taken in the test tube
(b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken
(c) In place of zinc, copper turnings are taken
(d) Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.
(a) In place of Zinc granules if we use Zinc dust reaction speed increases
Zn + 2HCl → ZnCl2 + H2
(c) If we use copper in place of Zinc there will be no reaction as copper will not react with dilute acids
(d) Sodium Zincate is produced if we use NaOH solution in place of acid
Zn + 2NaOH → Na2 ZnO2 + H2
(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 ?
(a) If we use baking soda instead of baking powder taste of the cake will be bitter. Upon heating baking soda sodium carbonate will be formed which will make the cake taste bitter.
(c) When tartaric acid is dissolved in water it gives out Hydrogen ions. Hydrogen ions reacts with Sodium Carbonate to produce carbon dioxide which will make the cake fluffy.
X is Calcium. When calcium carbonate reacts with HCl it gives out CO2 gas.
CaCO3 + HCl → CaCl2 + CO2 + H2O
When CO2 is passed into lime water it turns milky due to formation of Calcium carbonate.
Hence solution Y is lime water.
When chlorine gas is passed on dry lime water it gives bleaching powder which is used for disinfecting water.
A compound which is a byproduct of chloralkali process is NaOH. Hence, compound B is NaOH. When NaOH is treated with acidic oxide neutralization process occurs.
For Example: If NaOH is treated with carbon-di-oxide, it gives Sodium carbonate.
2NaOH + CO2 → Na2CO3 + H2O
The sulphate salt should be calcium sulphate which is white and soft substance. Calcium sulphate is popularly known as plaster of paris.
Plaster of paris has half molecule of water of crystallization. When we leave plaster of paris open for some time, it absorbs moisture to gain number of molecules of crystallization. This newly formed compound is called Gypsum which is hard to make moulds
- 2NaOH+ Zn → Na2ZnO2 + H2(g)
- NaOH + HCl → NaCl + H2O
- NaOH + CH3COOH → CH3COONa + H2O