NCERT Exemplar Solution Class 10 Science Chapter 2
NCERT Exemplar Solution Class 10 Science Chapter 2 Acids, Bases and Salts all Questions Answer Solution. NCERT Exemplar Class 10 Science Chapter 2 Solution PDF.
NCERT Exemplar Solution Class 10 Science Chapter 2: Overview
NCERT Exemplar Solution Class 10 Science Chapter 2 |
|
Board |
NCERT |
Topic |
Exemplar Problem Solution |
Class |
10 |
Subject |
Science |
Chapter |
2 |
Chapter Name |
Acids, Bases and Salts |
NCERT Exemplar Solution Class 10 Science Chapter 2 Acids, Bases and Salts
Multiple Choice Questions
1> What happens when a solution of an acid is mixed with a solution of a base in a test tube?
- The temperature of the solution increase
- The temperature of the solution decreases
- The temperature of the solution remains the same
- Salt formation takes place
- I only
- I and III
- II and III
- I and IV
Answer:- d) I and IV
Acid and base combines and neutralizes the mixture. These process is called as Neutralisation reaction. It is a exothermic reaction. Neutralisation reaction gives the by product of salt.
2> An aqueous solution turns red litmus blue. Excess addition of which of the following Solution would reverse the change ?
- Baking powder
- Lime
- Ammonium hydroxide solution
- Hydrochloric acid
Answer:- d) Hydrochloric acid
Hydrochloric acid is a strong acid. And when the solution turns red litmus paper to blue then the solution will be basic in nature. And when HCl is added to it then the Neutralization reaction occurs their which neutralizes the solution and reverse the change.
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
- Absorb the evolved gas
- Moisten the gas
- Absorb moisture from the gas
- Absorb Cl- ions from the evolved gas
Answer:- c) Absorb moisture from the gas
The role of calcium chloride used absorbs the moisture. Calcium is good dehydrating agent and it absorbs all the moisture.
4> Which of the following salts does not contain water of crystallisation?
- Blue Vitriol
- Baking soda
- Washing soda
- Gypsum
Answer:- b) Baking soda
Blue Vitriol, washing soda and Gypsum are in the crystalline structure, whereas the baking soda is amorphous in nature.
5> Sodium carbonate is a basic salt because it is a salt of
- Strong acid and strong base
- Weak acid and weak base
- Strong acid and weak base
- Weak acid and strong base
Answer:- d) Weak acid and strong base
Sodium carbonate is basis salt because it is a salt of weak acid Carbonate and strong base Sodium.
6> Calcium phosphate is present in tooth enamel. Its nature is
- Basic
- Acidic
- Neutral
- Amphoteric
Answer:- a) Basic
Calcium phosphate is Basic in nature. Because phosphate ions are Strong base hence it forms Calcium Phosphate basic.
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?
- Lemon juice
- Vinegar
- Common salt
- An antacid
Answer:- d) An antacid
The sample is acidic in nature, because it turns the pH paper yellowish-orange. If we add an antacid or basic solution in it so that it will turn the colour into greenish blue.
8> Which of the following gives the correct increasing order of acidic strength?
- Water < Acetic acid < Hydrochloric acid
- Water < Hydrochloric acid<Acetic acid
- Acetic acid < Water < Hydrochloric acid
- Hydrochloric acid< water <Acetic acid
Answer:- a) Water < Acetic acid < Hydrochloric acid
These is increasing order of acidic strength as water is neutral than acetic acid is weak acid and Hydrochloric acid is very strong acid in nature.
9> If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done ?
- Wash the hand with saline solution
- Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate
- After washing with plenty of water apply Solution of sodium hydroxide on the hand
- Neutralize the acid with a strong alkali
Answer:- b) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate
Acid is strong in nature so it damage the skin when it Is washed by the water it reduces the concentration of acid, and the paste of sodium Hydrogen Carbonate is basic in nature these will neutralizes the acids traces and give relief.
10> Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved ?
- I turns lime water milky
- II extinguishes a burning splinter
- III dissolves in a solution of sodium hydroxide
- IV has a pungent odour
- I and II
- I, II and III
- II, III, and IV
- I and IV
Answer:- b) I, II and III
When sodium Hydrogen Carbonate is added to acetic acid then these all is true thatextinguishes a burning splinter, dissolves in a solution of sodium hydroxide. The reaction evolves the CO2 gas which turns the lime water milky.
11> Common salt besides used in kitchen can also be used as the raw material for making
- Washing soda
- Bleaching powder
- Baking soda
- Slaked lime
- I and II
- I, II and IV
- I and III
- I, III, and IV
Answer:- c) I and III
Washing soda and Baking soda are these are made by using common salt.
12> One of the constituents of baking powder is sodium hydrogen carbonate, the other Constituent is
- Hydrochloric acid
- Tartaric acid
- Acetic acid
- Sulphuric acid
Answer:- b) Tartaric acid
Baking powder is made up by using sodium carbonate and tartaric acid which is a soft edible acid.
13> To protect tooth decay we are advised to brush our teeth regularly, the nature of the tooth paste commonly used is
- Acidic
- Neutral
- Basic
- Corrosive
Answer:- c) Basic
The nature of tooth paste should be basic in nature to prevent the tooth decay because the bacterial cavity or other microorganisms present in the mouth are acidic so that to it will be neutralize by the basic toothpaste.
14> Which of the following statements is correct about an aqueous solution of an acid and of a base?
- Higher the pH, stronger the acid
- Higher the pH, weaker the acid
- Lower the pH, stronger the base
- Lower the pH, weaker the base
Answer:- d) Lower the pH, weaker the base
Lower the pH i.e less than 7 is weaker base and higher than the 7 is strong acids. Hence lower the pH towards the 0 will be more weaker base.
15> The pH of the gastric juices released during digestion is
- Less than 7
- More than 7
- Equal to 7
- Equal to 0
Answer:- a) Less than 7
Gastric juice release during the digestion is basic in nature so on the pH scale it will be less than 7.
16> Which of the following phenomena occur, when a small amount of acid is added to water ?
- Ionisation
- Neutralisation
- Dilution
- Salt formation
- I and II
- I and III
- II and III
- II and IV
Answer:- b) I and III
When a small amount of acid is added to the water then the process of Ionisation and Dilution occurs in the water.
17> Which one of the following can be used as acid-base indicator by a visually impared student?
- Litmus
- Turmeric
- Vanilla essence
- Petunia leaves
Answer:- c) Vanilla essence
Acid base indicator is also known as olfactory indicator, the vanilla essence is olfactory indicator hence it can be used by the visually impared student.
18> Which of the following substances will not give Carbon dioxide on treatment with dilute acid?
- Marble
- Limestone
- Baking soda
- Lime
Answer:- d) lime
Lime will not give Carbon dioxide on treatment with dilute acid because it does not contain carbonates , all the other options contains carbonate hence they produce the CO2 .
19> Which of the following is acidic in nature ?
- Lime juice
- Human blood
- Lime water
- Antacid
Answer:- a) Lime juice
Lime juice is acidic in nature. Which contains the citric acid. Other are basic 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?
Fig. 2.1
- Bulb will not glow because electrolyte is not acidic
- Bulb will glow because NaOH is a strong base and furnishes ions for conduction
- Bulb will not glow because circuit is incomplete
- Bulb will not glow because it depends upon the type of electrolyte solution.
- I and III
- II and IV
- II only
- IV only
Answer:- c) II only
Bulb will glow because NaOH is a strong base and furnishes ions for conduction.
To glow the blub it needs a conductor which conducts the current NaOH is strong base which conducts the ions and hence bulb glow.
21> Which of the following is used for dissolution of gold?
- Hydrochloric acid
- Sulphuric acid
- Nitric acid
- Aqua regia
Answer:- d) Aqua regia
Nitric acid, sulphuric acid or Hydrochloric acid all of these doesn’t reacts over the gold. Because gold is a Nobel metal. Hence option D. Aqua regia is used for the dissolution of gold.
22> Which of the following is not a mineral acid?
- Hydrochloric acid
- Citric acid
- Sulphuric acid
- Nitric acid
Answer:- b) Citric acid
Citric acid is not a mineral acid because it is a organic acid.
23> Which among the following is not a base ?
- NaOH
- KOH
- NH4OH
- C2H5OH
Answer:- d) C2H5OH
C2H5OH is not a base it is a alcohol.
24> Which of the following statements is not correct ?
- All metal carbonates react with acid to give a salt, water and carbon dioxide
- All metal oxides react with water to give salt and acid
- Some metals react with acids to give salt and hydrogen
- Some non metal oxides react with water to form an acid
Answer:– b) All metal oxides react with water to give salt and acid
All metal oxides react with water to give salt and acid because these are basic in nature which gives the alkaline solution when dissolved in water.
25> Match the chemical substances given in column A with their appropriate application given in Column B
Column A |
Column B |
a) Bleaching powder |
I) Preparation of glass |
b) Baking soda | II) production of H2 and Cl2 |
c) Washing soda | III) Decolourisation |
d) Sodium chloride |
IV) antacid |
- A- II, B- I, C – iv , D- III
- A – III, B- II , C – IV, D – I
- A- III, B- IV, C – I, D – II
- A – II, B – IV, C – I, D – III
Answer:- c) A- III, B- IV, C – I, D – II
26> Equal Volumes of hydrochloric acid 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)
Fig. 2.2
- Red
- Yellow
- Yellowish- green
- Blue
Answer:- c)Yellowish- green
HCl is acid and NaOH is base so they both combines together to form a neutral solution. Hence yellowish-green colour will obtained.
27> Which of the following is (are) true when HCl (g) is passed through water?
- It does not ionise in the solution as it is a covalent compound.
- It ionises in the solution.
- It gives both Hydrogen and hydroxyl ion in the solution
- It forms hydronium ion in the solution due to the combination of Hydrogen ion with water molecule
- I only
- III only
- II and IV
- III and IV
Answer:- c) II and IV
When HCl gas is passed through the water the Ionisation takes place these separates the hydrogen gas and Chlorine molecule. These hydrogen gas combines with the water molecule these produces the Hydronium ions.
28> Which of the following statements is true for acids?
- Bitter and change red litmus to blue
- Sour and change red litmus to blue
- Sour and change blue litmus to red
- Bitter and change blue litmus to red
Answer:- c)Sour and change blue litmus to red
Acids turn blue litmus paper to red and the taste is sour .
29> Which of the following are present in a dilute aqueous solution of hydrochloric acid?
- H3O + + Cl-
- H3O+ + OH-
- Cl- + OH
- Unionised HCl
Answer:- a) H3O + + Cl–
When acid is added to the water the process of Ionisation takes place which separates the hydrogen ion these is added to the water Hydrogen it and forms hydronium ion and Chlorine.
30> Identify the correct representation of reaction occurring during chloralkali process
- 2NaCl(I) + 2H2O (I) → 2NaOH(I) + Cl2 (g) + H2(g)
- 2NaCl(aq) + 2H2O(aq) → 2NaOH(aq) + Cl2(g) + H2(aq)
- 2NaCl(aq) + 2H2O(I) → 2NaOH(aq) + Cl2(aq) + H2(aq)
- 2NaCl(aq) + 2H2O(I) → 2NaOH(aq) + Cl2(g) + H2(g)
Answer:- d) 2NaCl(aq) + 2H2O(I) → 2NaOH(aq) + Cl2(g) + H2(g)
These is the correct representation of the chloralkaliprocess.
Short answer questions
31> Match the acids given in Column A with their correct source given in Column B
Column A |
Column B |
a) Lactic acid | I) Tomato |
b) Acetic acid | II) Lemon |
c) Citric acid | III) Vinegar |
d) Oxalic acid | IV) Curd |
Answer:-
Column A Answers
- Lactic acid → iv) curd
- Acetic acid → iii) Vinegar
- Citric acid → ii) lemon
- Oxalic acid →I) Tomato
32> Match the important chemicals given in column A with the chemical formulae given in column B
Column A |
Column B |
a) Plaster of Paris | I) Ca(OH)2 |
b) Gypsum | II) CaSO4. ½ H2O |
c) Bleaching powder | III) CaSO4.2H2O |
d) Slaked lime | iv) CaOCl2 |
Answer:-
Column A Answer
- Plaster of Paris →II) CaSO4. ½ H2O
- Gypsum →III) CaSO4.2H2O
- Bleaching powder →IV) CaOCl2
- Slaked lime → I) Ca(OH)2
33> What will be the action of the following substances on litmus paper?
Dry HCl gas, Moistened NH3 gas, Lemon juice, Carbonated soft drink, curd, Soap Solution.
Answer:-
Dry HCl gas → No effect
Moistened NH3 gas → it turns litmus paper to blue
Lemon juice → it will turn litmus paper to red
Carbonated soft drink → it will turn litmus paper to blue
Curd → it will turn litmus paper to red
Soap Solution → it will turn litmus paper to blue colour
34> Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.
Answer:-
Ant sting contains the methanolic acid (HCOOH). Due to these acid we feel the pain if we rub the baking soda over the infecting part then it neutralizes the acid and gives the relief.
35> What happens when nitric acid is added to egg shell?
Answer:-
Egg shell which is made up of calcium carbonate, When nitric acid is added to it, the reaction takes place between them and it produces Calcium nitrate and CO2 gas.
36> A student prepared solutions of (I) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since both the solutions are Colourless, how will she distinguish between the two?
Answer:-
If the litmus paper is not available in laboratory then also the student can distinguish between the acid and base solution by using the indicators like phenolphthalein or natural indicators like China rose or turmeric etc.
37> How would you distinguish between baking powder and washing soda by heating ?
Answer:-
The difference between both of them is that the baking powder on heating release Carbon dioxide gas which is confirmed after a test i.e let the gas pass through the lime water then the lime water turns milky. These CO2 is not released in the washing soda because these reaction does not carried out on heating.
38> Salt A commonly used in bakery products on heating gets converted into another salt B which itself is used for removal of hardness of water and a gas C is evolved. The gas C when passed through like water, turns it milky, identify A, B, and C.
Answer:-
Salt A which is Commonly used in the bakery can be baking Soda i.e. Sodium Hydrogen Carbonate and it will turn into Sodium Carbonate after heating i.e. Salt B. This Evolves the gas C which is Carbon dioxide gas which when passed through the lime water then it turns water milky.
39> In one of the industrial processes used for manufacturer of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.
Answer:-
Here we know X is reacts with lime water to give the Y which is a Bleaching agent in chemical industry,
Hence
X will be Chlorine (Cl2)
Y will be Bleaching powder (CaOCl2)
And the reaction between them will occur as –
Ca(OH)2 (s) + Cl2 (g) → CaOCl2 (s) + H2O
40> Fill in the missing data in the following table.
Name of the salt |
Formula | Salt obtained from | ||
Base |
Acid |
|||
I) Ammonium
Chloride
|
NH4Cl | NH4OH | _ | |
II) Copper sulphate
|
_ | _ | H2SO4 | |
III) Sodium chloride
|
NaCl | NaOH | _ | |
IV) Magnesium nitrate
|
Mg(NO3)2 | _ | HNO3 | |
V) Potassium sulphate
|
K2SO4 | _ | _ | |
VI) Calcium nitrate
|
Ca(NO3)2 | Ca(OH)2 | _ | |
Answer :-
Name of the salt |
Formula | Salt obtained from | |
Base |
Acid |
||
i) Ammonium Chloride
|
NH4Cl | NH4OH | HCl |
ii) Copper Sulphate
|
CuSO4 | Cu(OH)2 | H2SO4 |
iii) Sodium Chloride
|
NaCl | NaOH | HCl |
iv) Magnesium Nitrate
|
Mg(NO3)2 | Mg(OH)2 | HNO3 |
v) Potassium Sulphate
|
K2SO4 | KOH | H2SO4 |
vi) Calcium nitrate
|
Ca(NO3)2 | Ca(OH)2 | HNO3 |
41> What are strong and weak acids ? In the following list of acids, separate strong acids from weak acids.
Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.
Answer:-
Weak acids
|
Strong acids |
Citric acid | Hydrochloric acid |
Acetic acid | Nitric acid |
Formic acid | Sulphuric acid |
42> When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.
Answer:-
The gas evolved during the chemical reaction is Hydrogen gas which is used in the hydrogenation of the oil.
The chemical reaction involved when the zinc metal is treated with dil. Solution of Hydrochloric acid is –
Zn + 2HCl → ZnCl2 + H2 ↑
Here, Hydrogen gas is evolving which can be confirmed by the test, let the gas pass near the burning flame, the pop up sound is listened which confirms the gas is Hydrogen.
Long Answer Questions
43> In the following schematic diagram for the preparation of Hydrogen gas as shown in figure 2.3 what would happen if following changes are made?
Fig. 2.3
- In place of zinc granules, same amount of zinc dust is taken in the test tube
Answer:- if zinc dust is taken at the place of zinc granules then the Hydrogen gas will Evolves with more speed.
- Instead of dilute sulphuric acid, dilute hydrochloric acid is taken
Answer:- it will not affect the solution more, the evolution of gas will be near about same in both cases.
- In place of zinc, copper turnings are taken
Answer:- if copper turnings taken at the place of zinc then there will not be evolution of gas.
- Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.
Answer:- Due to sodium hydroxide, taken at the place of dil. Sulphuric acid then the hydrogen gas will Evolved and the reaction will give a by-product of sodium zincate along with hydrogen gas.
44> For making cake, baking powder is taken. If at home your mother uses baking soda instead instead of baking powder in cake.
a> How will it affect the taste of the cake and why?
Answer:- it will turn the taste of cake into bitter. Because baking soda contains sodi6 hydrogen carbonate after heating it forms Sodium Carbonate. Hence it will be bitter in taste.
b> How can baking soda be converted into baking powder?
Answer:- The addition of correct amount of tartaric acid into the Sodium Hydrogen Carbonate turns it to the Sodium carbonate.
C> What is the role of tartaric acid added to baking soda ?
Answer:- The tartaric acid plays the role of Neutralisation which will turn the Sodium Hydrogen Carbonate into Sodium Carbonate. Hence it will not taste bitter.
45> A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identify X, Y, G and Z.
Answer:- According to the given information about X it can be concluded that X is acarbonate of Calcium. When it reacts with the hydrochloric acid then the evolution of CO2 gas takes place.
The reaction is carried out as –
CaCO3 + HCl → CaCl2 + CO2 + H2O
The passing of carbon dioxide gas though the lime turns it milky these is because it forms the calcium carbonate . Hence the solution y will be the lime water.
When Cl gas passed through dry CaOH2 it gives the product bleaching powder which is Z. Bleaching powder is used as the disinfecting agent.
Hence here,
X – calcium carbonate
Y – slaked lime
Z – Bleaching powder
G – Chlorine gas
46> A dry pellet of a common base B, when kept in open absorbs moisture and turns sticky. The compound is also a by-product of B is treated with an acidic oxide? Write a balanced chemical equation for one such Solution.
Answer:-
The compound B which is a common base will be Sodium hydroxide (NaOH).
When NaOH is added to the acidic oxide it gives the salt and water hence the chemical reaction it undergoes is Neutralization reaction.
These reaction will be processed as –
2NaOH + CO2 → Na2CO3 + H2O
47> A sulphate salt of Group 2 element of the periodic table is a white, soft substance, which can be moulded into different shapes by making its dough , when this compound is left in open for some time, it becomes a solid mass and cannot be used for moulding purposes. Identify the Sulphate salt and why does it show such a behaviour? Give the reaction involved.
Answer:-
The given information is about the sulphate salt of Group 2 these would be Calcium Sulphate. It is also known as plaster of Paris or ( POP ). When it is left in the open for some time it absorbs the moisture from the atmosphere and hence it becomes harden as solid mass, these new compound is Gypsum. The reaction involved in it is crystallization reaction.
It is proceeds as –
CaSO4. ½ H2O + l ½ H2O → CaSO4.2H2O
Plaster of Paris gypsum
48> Identify the Compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C.
Fig. 2.4
Answer:-
According to the figure,
The reaction could be –
- 2NaOH + Zn → Na2ZnO2 + H2
- NaOH + HCl → NaCl + H2O
- NaOH + CH3COOH → CH3COONa + H2O
Thus ,
X will be sodium hydroxide – NaOH
A will be Sodium zincate – Na2ZnO2
B will be Sodium Chloride – NaCl
C will be Sodium acetate – CH3COONa
Here is your solution of NCERT Exemplar Class 10 Science Chapter 2 Acids, Bases and Salts
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