Class 10 Science Acids, Bases and Salts questions with solutions

Q 1 :

What is the nature of the new product which is formed by the action of water on quick lime?

Neutral
Acidic
Amphoteric
Basic

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(4)

When quick lime is added to water, it reacts to form slaked lime $(C a {(O H)}_{2})$ . Slaked lime or calcium hydroxide is basic in nature because it dissociates into $O H^{-}$ ions when dissolved in aqueous solution.

Q 2 :

The pH range most conducive for life of fresh water plants and animals is:

6.5–7.5
2.0–3.5
3.5–5.0
9.0–10.5

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(1)

A neutral pH is most conducive for life of fresh water plants and animals and the pH range 6.5–7.5 is almost neutral.

Q 3 :

Phenolphthalein turns acids to _______ solution.

colourful
colourless
pink
orange

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(2)

Phenolphthalein is used as an indicator in acid–base titrations. For this application, it turns acids to colourless solutions and bases to pink solutions.

Q 4 :

Which one of the following is acidic in nature?

Gastric juice
Sodium hydroxide solution
Lime water
Blood plasma

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(1)

Gastric juice is acidic in nature due to the presence of hydrochloric acid (HCl). This acid is secreted by the stomach lining and plays a crucial role in digestion by providing an acidic environment. In contrast, sodium hydroxide solution (b) is a base, lime water (c) is slightly basic due to the presence of calcium hydroxide, and blood plasma (d) is slightly alkaline with a pH around 7.4, necessary for proper physiological functions.

Q 5 :

An aqueous solution ‘A’ turns phenolphthalein solution pink. On addition of an aqueous solution ‘B’ to ‘A’, the pink colour disappears. The following statement is true for solution ‘A’ and ‘B’

A is strongly basic and B is a weak base
A is strongly acidic and B is a weak acid.
A has pH greater than 7 and B has pH less than 7
A has pH less than 7 and B has pH greater than 7

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(3)

Phenolphthalein solution turns pink in basic solutions. Hence, solution A lies in the pH range of above 7. On adding solution B, the pink colour disappears, hence it has a pH less than 7.

Q 6 :

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

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(3)

When we consume acidic food or drinks, the pH of the mouth falls to 5.5 due to which tooth decay occurs. This lowering of pH within the mouth can lead to dental plaque. To protect this, doctors advise to brush the teeth with the toothpaste which are basic in nature as it neutralises the acidic condition inside the mouth. Hence, the nature of the toothpaste should be basic.

Q 7 :

Which one of these acid-base indicators is used by a visually impaired student?

Litmus
Turmeric
Vanilla
Phenolphthalein

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(3)

Vanilla essence is used as an acid-base indicator because of its smell which helps visually challenged people to realise the change in pH.

Q 8 :

When you add a few drops of acetic acid to a test-tube containing sodium bicarbonate powder, which one of the following is your observation?

No reaction takes place
A colourless gas with pungent smell is released with brisk effervescence
A brown coloured gas is released with brisk effervescence
Formation of bubbles of a colourless and odourless gas

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(4)

When a few drops of acetic acid is added to the test tube containing sodium bicarbonate powder, sodium acetate is formed along with the release of colourless and odourless CO? gas which can be observed as the bubbles in the test tube.

Q 9 :

A student puts a drop of reaction mixture of a saponification reaction first on a blue litmus paper and then on a red litmus paper. He may observe that:

There is no change in the blue litmus paper and the red litmus paper turns white.
There is no change in the red litmus paper and the blue litmus paper turns red.
There is no change in the blue litmus paper and the red litmus paper turns blue.
No change in colour is observed in both the litmus papers.

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(3)
Saponification is the alkaline hydrolysis of the fatty acid esters. Hence, the solution is basic, bases with blue litmus gives no colour change. Whereas, on dipping red litmus paper in a mixture of saponification reaction it turns blue

Q 10 :

The pH value of a sample of hydrochloric acid is 2. pH value of this sample when diluted by adding water will be:

less than 2 but more than 0
more than 2 but less than 7
more than 7
no change in pH

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(2)

When we add water to the solution of hydrochloric acid (pH = 2), the pH will increase till 7 but it will be less than 7 as it contains more hydrogen ions ( $H^{+}$ ions) as compared to hydroxide ions ( $O H^{-}$ ions). So, the pH on dilution will be more than 2 but less than 7.

Q 11 :

While preparing soap a small quantity of common salt is generally added to the reaction mixture of vegetable oil and sodium hydroxide. Which one of the following may be the purpose of adding common salt?

To reduce the basic nature of the soap
To make the soap neutral
To enhance the cleansing power of the soap
To favour the precipitation of the soap

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(4)

A small quantity of common salt is generally added to the reaction mixture of vegetable oil and sodium hydroxide to favour the precipitation of the soap because by adding salt to the suspension mixture, soap is precipitated as solid. This process is called salting out of soap

Q 12 :

When a small amount of acid is added to water, the phenomena which occur are

(A) Dilution
(B) Neutralisation
(C) Formation of $H_{3} O^{+}$ ions
(D) Salt formation

The correct statements are :

(A) and (C)
(B) and (D)
(A) and (B)
(C) and (D)

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(1)

When a small amount of acid is added to water, the phenomena which occur are dilution and formation of $H_{3} O^{+}$ ions. When water is added, a concentrated acid is turned into a dilute acid. This process is called dilution of acid. A dilute acid is an aqueous solution in which acid undergoes ionisation and releases hydronium ions $(H_{3} O^{+})$

Q 13 :

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.
Neutralise the acid with a strong alkali.

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(2)

If a few drops of a concentrated acid accidentally spills over the hand of a student then he should wash his hands immediately with plenty of water as it will dilute the acid and wash it out. Any remaining acid should be neutralised by applying the paste of sodium hydrogen carbonate.

Q 14 :

Which one of the following types of medicines is used for treating indigestion?

Antibiotic
Analgesic
Antacid
Antiseptic

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(3)

Antacids such as sodium bicarbonate and magnesium hydroxide etc. are used in treating indigestion. They are basic in nature and react with excess acid present in the stomach and neutralise it.

Q 15 :

Which of the following is used for dissolution of gold?

Hydrochloric acid
Sulphuric acid
Nitric acid
Aqua regia

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(4)

Aqua regia is a mixture of hydrochloric acid and nitric acid in the ratio 3:1 and it can dissolve noble metals such as gold, palladium, and platinum, which however, are not soluble in either of the acids alone.

Q 16 :

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 is to:

Absorb the evolved gas
Moisten the gas
Absorb moisture from the gas
Absorb $C l^{-}$ ions from the evolved gas

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(3)

Calcium chloride is a drying agent used in the guard tube to absorb the moisture present in the air during hydrogen chloride gas preparation. Moisture must be removed to prevent the gas from forming white fumes, which occurs due to its reaction with water.

Q 17 :

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?

(a) Bulb will not glow because electrolyte is not acidic.
(b) Bulb will glow because NaOH is a strong base and furnishes ions for conduction.
(c) Bulb will not glow because circuit is incomplete.
(d) Bulb will not glow because it depends upon the type of electrolytic solution.

(i) and (iii)
(ii) and (iv)
(ii) only
(iv) only

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(2)
Bulb will glow because NaOH is a strong base that dissociates completely in water into $N a^{+}$ ions and $O H^{-}$ ions which are responsible for electrical conductivity.

Q 18 :

10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be:

4 mL
8 mL
12 mL
16 mL

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(4)

Given: 10 mL of NaOH requires 8 mL of HCl.
Let X be the amount of HCl required to neutralise the 20 mL of NaOH.

20 mL of NaOH require = X HCl
X = (20 × 8) / 10
X = 16 mL

Q 19 :

Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?

$H_{2} S O_{4}$
HCl
$H N O_{3}$
All of these

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(3)

Nitric acid $(H N O_{3})$ does not give hydrogen gas on reacting with metals (except Mg and Mn) because it is a strong oxidising agent and oxidises the evolved H? gas to water and itself gets reduced to the oxides of nitrogen. Whereas metals such as magnesium and manganese react with very dilute $H N O_{3}$ to evolve $H_{2}$ gas.

Q 20 :

Which of these graphs shows how the pH of milk changes as it forms curd?

a
b
c
d

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(1)

Fresh milk has an acidic character due to its pH of 6.4 to 6.8. By the action of bacteria, this milk is transformed into curd, which further increases the curd's acidity and lowers its pH from 6 to less than 6.

Q 21 :

Which of the following salts do not contain water of crystallisation?

Blue vitriol
Baking soda
Washing soda
Gypsum

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(2)

Baking soda is sodium bicarbonate $(N a H C O_{3})$ in anhydrous form without any water of crystallisation.
Other options:
Blue Vitriol: It is hydrated salt of copper sulphate containing 5 molecules of water of crystallisation $(C u S O_{4} \cdot 5 H_{2} O)$ .
Washing soda: It is hydrated salt of sodium carbonate containing 10 molecules of water of crystallisation $(N a_{2} C O_{3} \cdot 10 H_{2} O) .$
Gypsum: It is hydrated salt of calcium sulphate containing 2 molecules of water of crystallisation $(C a S O_{4} \cdot 2 H_{2} O)$ .

Q 22 :

The chemical formula for plaster of Paris is:

$C a S O_{4} \cdot 2 H_{2} O$
$C a S O_{4} \cdot H_{2} O$
$C a S O_{4} \cdot 1 / 2 H_{2} O$
$2 C a S O_{4} \cdot H_{2} O$

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(3)

The chemical formula of plaster of Paris is $C a S O_{4} \cdot 1 / 2 H_{2} O$ . The half a molecule of water in the formula means that two molecules of $C a S O_{4}$ share one molecule of water so that the effective water of crystallisation for one $C a S O_{4}$ unit comes to half a molecule of water.

Q 23 :

Baking soda is a mixture of:

Sodium carbonate and acetic acid
Sodium carbonate and tartaric acid
Sodium hydrogen carbonate and tartaric acid
Sodium hydrogen carbonate and acetic acid

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(3)

Baking soda is a mixture of sodium hydrogen carbonate $(N a H C O_{3})$ and mild edible tartaric acid.

Q 24 :

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.

(i) and (ii)
(i), (ii) and (iii)
(ii), (iii) and (iv)
(i) and (iv)

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(2)

The gas evolved is carbon dioxide gas and it has the property to extinguish a burning splinter. It can turn lime water milky and gets dissolved in a solution of sodium hydroxide to form sodium carbonate. It is an odourless gas, hence the statement (iv) is false.

Q 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 $H_{2}$ and $C l_{2}$

(C) Washing soda (iii) Decolourisation

(D) Sodium chloride (iv) Antacid

Column ‘A’	Column ‘B’
(A) Bleaching Powder	(i) Preparation of glass
(B) Baking soda	(ii) Production of $H_{2}$ and $C l_{2}$
(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)

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(3)

Bleaching powder $(C a O C l_{2})$ :
It is used for bleaching or decolourisation of clothes. Bleaching powder on reaction with water decomposes and releases chlorine, which acts as an oxidising, bleaching and disinfecting agent.
Baking soda $(N a H C O_{3})$ :
It is used as an antacid for relieving stomach acidity. They react with excess acid in the stomach and neutralises it.
Washing soda $(N a_{2} C O_{3})$ :
It is used in preparation of glass, soap and paper industries.
Sodium chloride (NaCl):
Aqueous sodium chloride is used for the production of $H_{2}$ and $C l_{2}$ gases on electrolysis.

Q 26 :

Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?

FeO
$F e_{2} O_{3}$
$F e_{3} O_{4}$
$F e_{2} O_{3} a n d F e_{3} O_{4}$

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(3)

On prolonged heating with steam, iron produces a mixed oxide of $F e_{3} O_{4}$ with the evolution of hydrogen gas.

$3 F e + 4 H_{2} O ⟶ F e_{3} O_{4} + 4 H_{2}$

Topic Question Set

Q 1 :

What is the nature of the new product which is formed by the action of water on quick lime?

Q 2 :

The pH range most conducive for life of fresh water plants and animals is:

Q 3 :

Phenolphthalein turns acids to _______ solution.

Q 4 :

Which one of the following is acidic in nature?

Q 5 :

An aqueous solution ‘A’ turns phenolphthalein solution pink. On addition of an aqueous solution ‘B’ to ‘A’, the pink colour disappears. The following statement is true for solution ‘A’ and ‘B’

Q 6 :

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

Q 7 :

Which one of these acid-base indicators is used by a visually impaired student?

Q 8 :

When you add a few drops of acetic acid to a test-tube containing sodium bicarbonate powder, which one of the following is your observation?

Q 9 :

A student puts a drop of reaction mixture of a saponification reaction first on a blue litmus paper and then on a red litmus paper. He may observe that:

Q 10 :

The pH value of a sample of hydrochloric acid is 2. pH value of this sample when diluted by adding water will be:

Q 11 :

While preparing soap a small quantity of common salt is generally added to the reaction mixture of vegetable oil and sodium hydroxide. Which one of the following may be the purpose of adding common salt?

Q 12 :

When a small amount of acid is added to water, the phenomena which occur are

(A) Dilution
(B) Neutralisation
(C) Formation of $H_{3} O^{+}$ ions
(D) Salt formation

The correct statements are :

Q 13 :

If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done?

Q 14 :

Which one of the following types of medicines is used for treating indigestion?

Q 15 :

Which of the following is used for dissolution of gold?

Q 16 :

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 is to:

Q 18 :

10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be:

Q 19 :

Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?

Q 20 :

Which of these graphs shows how the pH of milk changes as it forms curd?

Q 21 :

Which of the following salts do not contain water of crystallisation?

Q 22 :

The chemical formula for plaster of Paris is:

Q 23 :

Baking soda is a mixture of:

Q 24 :

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.

Q 26 :

Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?

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Topic Question Set

Q 1 : What is the nature of the new product which is formed by the action of water on quick lime?

Q 2 : The pH range most conducive for life of fresh water plants and animals is:

Q 3 : Phenolphthalein turns acids to _______ solution.

Q 4 : Which one of the following is acidic in nature?

Q 5 : An aqueous solution ‘A’ turns phenolphthalein solution pink. On addition of an aqueous solution ‘B’ to ‘A’, the pink colour disappears. The following statement is true for solution ‘A’ and ‘B’

Q 6 : To protect tooth decay we are advised to brush our teeth regularly. The nature of the tooth paste commonly used is:

Q 7 : Which one of these acid-base indicators is used by a visually impaired student?

Q 8 : When you add a few drops of acetic acid to a test-tube containing sodium bicarbonate powder, which one of the following is your observation?

Q 9 : A student puts a drop of reaction mixture of a saponification reaction first on a blue litmus paper and then on a red litmus paper. He may observe that:

Q 10 : The pH value of a sample of hydrochloric acid is 2. pH value of this sample when diluted by adding water will be:

Q 11 : While preparing soap a small quantity of common salt is generally added to the reaction mixture of vegetable oil and sodium hydroxide. Which one of the following may be the purpose of adding common salt?

Q 12 : When a small amount of acid is added to water, the phenomena which occur are (A) Dilution (B) Neutralisation (C) Formation of H3O+ ions (D) Salt formation The correct statements are :

Q 13 : If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done?

Q 14 : Which one of the following types of medicines is used for treating indigestion?

Q 15 : Which of the following is used for dissolution of gold?

Q 16 : 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 is to:

Q 18 : 10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be:

Q 19 : Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?

Q 20 : Which of these graphs shows how the pH of milk changes as it forms curd?

Q 21 : Which of the following salts do not contain water of crystallisation?

Q 22 : The chemical formula for plaster of Paris is:

Q 23 : Baking soda is a mixture of:

Q 24 : 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.

Q 26 : Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?

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Q 1 :

What is the nature of the new product which is formed by the action of water on quick lime?

Q 2 :

The pH range most conducive for life of fresh water plants and animals is:

Q 3 :

Phenolphthalein turns acids to _______ solution.

Q 4 :

Which one of the following is acidic in nature?

Q 5 :

An aqueous solution ‘A’ turns phenolphthalein solution pink. On addition of an aqueous solution ‘B’ to ‘A’, the pink colour disappears. The following statement is true for solution ‘A’ and ‘B’

Q 6 :

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

Q 7 :

Which one of these acid-base indicators is used by a visually impaired student?

Q 8 :

When you add a few drops of acetic acid to a test-tube containing sodium bicarbonate powder, which one of the following is your observation?

Q 9 :

A student puts a drop of reaction mixture of a saponification reaction first on a blue litmus paper and then on a red litmus paper. He may observe that:

Q 10 :

The pH value of a sample of hydrochloric acid is 2. pH value of this sample when diluted by adding water will be:

Q 11 :

While preparing soap a small quantity of common salt is generally added to the reaction mixture of vegetable oil and sodium hydroxide. Which one of the following may be the purpose of adding common salt?

Q 12 :

When a small amount of acid is added to water, the phenomena which occur are

(A) Dilution
(B) Neutralisation
(C) Formation of $H_{3} O^{+}$ ions
(D) Salt formation

The correct statements are :

Q 13 :

If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done?

Q 14 :

Which one of the following types of medicines is used for treating indigestion?

Q 15 :

Which of the following is used for dissolution of gold?

Q 16 :

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 is to:

Q 18 :

10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be:

Q 19 :

Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?

Q 20 :

Which of these graphs shows how the pH of milk changes as it forms curd?

Q 21 :

Which of the following salts do not contain water of crystallisation?

Q 22 :

The chemical formula for plaster of Paris is:

Q 23 :

Baking soda is a mixture of:

Q 24 :

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.

Q 26 :

Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?