NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts

Read NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts below, students should study NCERT Exemplar class 10 Science available on Studiestoday.com with solved questions and answers. These chapter wise answers for class 10 Science Exemplar problems have been prepared by teacher of Grade 10. These NCERT Exemplar class 10 Science solutions have been designed as per the latest NCERT syllabus for class 10 and if practiced thoroughly can help you to score good marks in standard 10 Science class tests and examinations

Multiple Choice Questions........................


Question 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 1: (d) (i) and (iv) 

As acid is combined with a base solution, a neutralisation reaction occurs. The exothermic reaction of neutralisation results in the formation of salt.

 

Question 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 2:  (d) Hydrochloric acid

If the solution switches the colour of red litmus to blue, it's a simple solution. Since the effect can be neutralised by adding an acid, (d) is the correct response.

 

Question 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 3: (c) absorb moisture from the gas

Calcium is an excellent dehydrator. It has the capacity to absorb water. As a result, it is used in industry as a desiccant to dry gases and hydrocarbons.

 

Question 4:  Which of the following salts does not contain water of crystallisation?

(a) Blue vitriol

(b) Baking soda

(c) Washing soda

(d) Gypsum 

Solution 4: (b) Baking soda

Baking soda is a white amorphous powder, while the other salts listed in the question are crystalline.

 

Question 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 5: (d) weak acid and strong base

Solid salt is made up of weak acid and strong base. Sodium is a solid base, and carbonate is a weak acid in this situation.

 

Question 6:  Calcium phosphate is present in tooth enamel. Its nature is

(a) basic

(b) acidic

(c) neutral

(d) amphoteric 

Solution 6: (a) basic

Calcium phosphate contains the phosphate ion, which is a solid base and forms a strong salt. As a consequence, calcium phosphate is a basic mineral.

 

Question 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 7: (d) An antacid

The acidic nature of the sample is confirmed when the sample solution turns the pH paper yellowish-orange. We need to apply an antacid to turn the hue greenish-blue.

 

Question 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 8: (a) Water < Acetic acid < Hydrochloric acid

In its purest form, water is neutral, acetic acid is a mild organic acid, and hydrochloric acid is a solid acid.

 

Question 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 a solution of sodium hydroxide on the hand

(d) Neutralise the acid with a strong alkali 

Solution 9: (b) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate

The acid concentration can be decreased by washing the affected hand with plenty of water. Any remaining acid can be neutralised with a paste of Hydrogen carbonate, which is a simple substance. While NaOH is a base, it is corrosive in nature and is therefore not used to neutralise acids.

 

Question 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 10:  (a) (i) and (ii)

Carbon dioxide gas is produced by the reaction of sodium hydrogen carbonate and acetic acid. CO2 turns the lime water milky and puts out a splinter fire.

  

Question 11:  Common salt besides being used in the 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 11:  (a) (i) and (ii)

Common salt besides being used in the kitchen can also be used as the raw material for making washing soda and bleaching powder.

 

Question 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 12: (b) tartaric acid

Baking powder is made with a mild edible acid and Sodium Hydrogen Carbonate. In this case, acetic or citric acid may be substituted for tartaric acid.

 

Question 13:  To protect tooth decay we are advised to brush our teeth regularly. The nature of the toothpaste commonly used is

(a) acidic

(b) neutral

(c) basic

(d) corrosive 

Solution 13:  (c) Basic

Because of bacterial activity in the mouth, teeth will be acidic. Toothpaste would be neutral in nature to neutralise the acid.

 

Question 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 14:  (d) (ii) and (iv)

Acids are those with a PH below 7; the lower the PH, the stronger the acid; similarly, bases are those with a PH greater than 7. The higher the PH, the more acidic it will be.

 

Question 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 15:  (a) less than 7

To ensure quick breakdown of food particles, the PH is acidic to below 7. Stomach juices typically have a pH of 3.

 

Question 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 16:  (b) (i) and (iii)

Ionisation and dilution occurs when a small amount of acid is added to water.

 

Question 17:  Which one of the following can be used as an acid-base indicator by a visually impaired student?

(a) Litmus

(b) Turmeric

(c) Vanilla essence

(d) Petunia leaves 

Solution 17:  (c) Vanilla essence

Since vanilla essence is an olfactory indicator, visually impaired students may use it as an acid-base indicator.

 

Question 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 18:  (d) Lime

Carbonates are found in granite, limestone, and baking soda, which contain CO2. Lime is made up of Hydroxide, which doesn't contain CO2.

 

Question 19:  Which of the following is acidic?

(a) Lime juice

(b) Human blood

(c) Lime water

(d) Antacid 

Solution 19: (a) Lime juice

Citric acid is present in lime juice. As a result, it has an acidic in nature.

 

Question 20:  In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus was set up. Which among the following statement(s) is(are) correct?

(i) Bulb will not glow because the 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 the 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

Solution 20:  (c) (ii) only

Bulb will glow because NaOH is a strong base and furnishes ions for conduction.

 

Question 21:  Which of the following is used for dissolution of gold?

(a) Hydrochloric acid

(b) Sulphuric acid

(c) Nitric acid

(d) Aqua regia 

Solution 21: (d) Aqua regia

Since gold is a noble metal that does not react with strong acids, aqua regia, a mixture of nitric and hydrochloric acid in a 1:3 ratio, is used to dissolve it.

 

Question 22:  Which of the following is not a mineral acid?

(a) Hydrochloric acid

(b) Citric acid

(c) Sulphuric acid

(d) Nitric acid 

Solution 22: (b) Citric acid 

Since citric acid is an organic acid, it is the correct response.

 

Question 23:  Which among the following is not a base?

(a) NaOH

(b) KOH

(c) NH4OH

(d) C2H5 OH 

Solution 23:  (d) C2H5 OH

C2H5OH is not a base infact it is alcohol.

 

Question 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 24:  (b) All metal oxides react with water to give salt and acid 

Since metal oxides are basic in nature, when dissolved in water, they produce an alkaline solution.

 

NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts

 

Question 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

NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts

(a) Red

(b) Yellow

(c) Yellowish green

(d) Blue 

Solution 26: (c) Yellowish green 

Because of the neutralisation that occurs between the HCL and NaOH solution, the pH will remain neutral, resulting in a yellowish-green zone on the pH paper.

 

Question 27:  Which of the following is(are) true when HCl (g) is passed through water?

(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

(a) (i) only

(b) (iii) only

(c) (ii) and (iv)

(d) (iii) and (iv) 

Solution 27:  (c) (ii) and (iv)

HCL is a strong acid that fully ionises in water, producing both hydrogen and chlorine. Hydronium ions are formed when hydrogen atoms combine with water molecules.

 

Question 28:  Which of the following statements is true for acids?

(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 

Solution 28:  (c) Sour and change blue litmus to red

Acids are sour and change blue litmus to red.

 

Question 29:  Which of the following are present in a dilute aqueous solution of hydrochloric acid?

(a) H3O+ + Cl

(b) H3O+ + OH

(c) Cl– + OH

(d) unionised HCl  

Solution 29: (a) H3O+ + Cl

Acid releases hydrogen, which reacts with a water molecule to form the Hydronium ion.

 

Question 30:  Identify the correct representation of reaction occurring during the chloralkali process

(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) 

Solution 30:  (d) 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + Cl2 (g) + H2 (g) 

Correct representation of reaction occurring during the chloralkali process is

2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + Cl2 (g) + H2 (g)

 

Short Answer Questions..............................


NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts

 

Question 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. 

Solution 33:

NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts


Question 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. 

Solution 34:   Methanoic acid is released by ant stings. HCOOH is the chemical formula for methanoic acid. The pain caused by an ant sting can be relieved by rubbing baking soda on the affected region.

 

Question 35:  What happens when nitric acid is added to eggshell? 

Solution 35:   Eggshell, which is made up of Calcium carbonate, was dissolved by nitric acid. When calcium carbonate reacts with nitric acid, calcium nitrate and carbon dioxide gas are produced.

 

Question 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? 

Solution 36:  To determine the type of the solution, students may use the Phenolphthalein predictor.

  

Question 37:  How would you distinguish between baking powder and washing soda by heating? 

Solution 37:   When baking powder is heated, CO2 is released, which can be confirmed by transferring the evolved gas into milky lime water. When you heat washing soda, this reaction will not occur.

 

Question 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 lime water, turns it milky. Identify A, B and C. 

Solution 38:   Baking soda (Sodium Hydrogen Carbonate) turns into sodium carbonate (Salt B) when heated. Gas C causes lime water to turn milky, indicating that it is CO2.  

 

Question 39:   In one of the industrial processes used for the manufacture of sodium hydroxide, a gas X is formed as a by-product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in the chemical industry. Identify X and Y, giving the chemical equation of the reactions involved. 

Solution 39:

X is Chlorine (Cl2)

Y is Bleaching powder (CaOCl2)

Ca(OH)2 (s) + Cl2 (g) →  CaOCl2 (s) + H2O — Calcium oxychloride (bleaching powder)

 

NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts

 

Question 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. 

Solution 41:   Strong acids are those that get completely ionized and weak acids are those that get partially ionized.

NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts

 

Question 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. 

Solution 42:   As Zinc reacts with a dilute acid solution, the following reaction occurs, resulting in the release of hydrogen gas.

Zn + 2HCl → ZnCl2 + H2

When Hydrogen gas is brought close to a burning flame, it emits a popping sound, indicating that it has evolved.

 

Long Answer Questions..............................


Question 43:  In the following schematic diagram for the preparation of hydrogen gas as shown in given figure, what would happen if the following changes are made?

NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts

(a) In place of zinc granules, the 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. 

Solution 43:

(a) In place of Zinc granules if we use Zinc dust reaction speed increases.

(b) Instead of dilute sulphuric acid if we use dilute hydrochloric acid zinc Chloride is formed

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→ Na2ZnO2+ H2

 

Question 44:  For making a cake, baking powder is taken. If at home, your mother uses baking soda instead of baking powder in cake,

(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? 

Solution 44:

a) The cake would taste sour if we use baking soda instead of baking powder. When baking is heated, soda sodium carbonate is made, which gives the cake a bitter taste.

2NaHCO3 + Heat Na2Co3 + CO2 + H2O

b) By applying an edible weak acid like tartaric acid to baking soda, it can be turned into baking powder.

c) As tartaric acid is dissolved in water, hydrogen ions are released. Carbon dioxide is produced when hydrogen ions react with sodium carbonate, making the cake fluffy.

 

Question 45:  A metal carbonate X on reacting with 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 the anode during electrolysis of brine is passed on dry Y, and it gives a compound Z, used for disinfecting drinking water. Identity X, Y, G and Z. 

Solution 45:  Calcium is X. Calcium carbonate produces CO2 gas as it reacts with HCl.

CaCO3 + HCl→ CaCl2+CO2+H2O

Calcium carbonate is formed when CO2 is applied to lime water, causing it to turn milky. Solution Y is therefore lime water.

When chlorine gas is passed through dry lime water, bleaching powder is formed, which is then used to disinfect the water.

 

Question 46:  A dry pellet of a common base B, when kept in the open absorbs moisture and turns sticky. The compound is also a by-product of the chloralkali process. Identify B. What type of reaction occurs when B is treated with an acidic oxide? Write a balanced chemical equation for one such solution. 

Solution 46:   The chloralkali process produces NaOH, which is a byproduct. As a result, compound B is NaOH.

The neutralisation process occurs when NaOH is treated with acidic oxide. When NaOH is treated with carbon dioxide, for example, sodium carbonate is formed.

2NaOH + CO2 →Na2CO3 + H2O

 

Question 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 the 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 behaviour? Give the reaction involved. 

Solution 47:   Calcium sulphate, a white and soft material, should be used as the sulphate salt. Plaster of Paris is a calcium sulphate compound.

Plaster of Paris contains half a molecule of water during the crystallisation process. When we leave plaster of Paris open for a while, it absorbs moisture and forms a number of crystallisation molecules. Gypsum is the name given to this newly formed compound, which is difficult to mould.

 

Question 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.

NCERT Exemplar Solutions Class 10 Science Acids Bases And Salts

Solution 48:

1) 2NaOH + Zn→ Na₂ZnO₂ + H2 (g)

2) NaOH + HCl →NaCl + H2O

3) NaOH + CH3COOH→ CH3COONa + H2O                                                              

Compound X is determined to be Sodium Zincate by the following reaction.

Chapter 16 Sustainable Management of Natural Resources
NCERT Exemplar Solutions Class 10 Science Management of Natural Resources