Class 7- Chapter 4 - Acids, Bases and Salts - 4 Worksheets with Answer Key - CBSE Class Notes Online

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Acids, Bases and Salts – Worksheets with Answers

These worksheets are developed for the chapter “Acids, Bases and Salts.” This chapter deals with the basic concepts of acids, bases, and their properties, along with the formation of salts. The worksheets, including solved and unsolved versions, are intended to enhance learning and understanding of these concepts.

Key topics covered in the chapter and addressed through these worksheets include-

Properties of Acids and Bases- Understanding the general properties of acids and bases, like taste and effect on indicators.
Formation of Salts- Learning about how acids and bases react to form salts, and the properties of these salts.
Neutralisation- Exploring the concept of neutralisation, where acids and bases cancel each other’s effects.

The solved worksheets provide guidance on how to approach these topics, while the unsolved worksheets allow for practice and self-assessment.

Also Check – A Young Explorer’s Guide to Acids and Bases

Worksheet 1 -Acids, Bases and Salts – Student Worksheet (Unsolved)

Fill in the blanks-

(a) Acids are substances that taste __________ and turn blue litmus paper __________.

(b) Bases feel __________ to the touch and turn red litmus paper __________.

(d) Litmus, a natural indicator, is extracted from __________.

(e) The reaction between hydrochloric acid and sodium hydroxide produces __________ as one of the products.

Mark ‘T’ if the statement is true and ‘F’ if it is false-

(a) Acids and bases are corrosive in nature. (T/F)

(b) Litmus is a synthetic indicator. (T/F)

(d) Factory wastes are usually neutralised with acids. (T/F)

Tick (✓) mark the correct answer in each of the following-

(a) Which of the following is a natural indicator?

(i) Phenolphthalein

(ii) Litmus

(iii) Methyl orange

(iv) Bromothymol blue

(b) Hydrochloric acid reacts with sodium hydroxide to form-

(i) Sodium carbonate

(ii) Sodium chloride

(iii) Sodium bicarbonate

(iv) Sodium sulphate

Match the items of Column I with those given in Column II-

Column I

(a) Acids

(b) Bases

(d) Litmus

Column II

(i) Turns red in acidic solutions

(ii) Are corrosive

(iii) Form salt and water

(iv) Feel slippery

What is the role of neutralisation in environmental protection, particularly regarding factory waste?

Also Check – What is a Neutralisation Reaction?- Explained

How does the pH of soil affect plant growth, and what measures are taken to maintain the right pH balance?

Explain the difference in properties between acidic and basic salts.

Why are substances like baking soda and vinegar commonly used in household cleaning?

Describe the safety measures that should be taken while handling acids and bases.

Discuss the use of acids and bases in food preservation and cooking, providing specific examples.

Match the items of Column I with suitable items in Column II-

Column I
- (a) Citric acid
- (b) Sodium hydroxide
- (c) Vinegar
- (d) Calcium hydroxide
Column II
- (i) Manufacture of soaps
- (ii) Food preservation
- (iii) Aerated drinks
- (iv) Baking powder

Also Check – NCERT Exemplar Solutions- Class 7 Science Chapter – 5- Acids, Bases and Salts

Worksheet 1 -Acids, Bases and Salts – Solved Worksheet

Fill in the blanks-

(a) Acids are substances that taste sour and turn blue litmus paper red.
(b) Bases feel slippery to the touch and turn red litmus paper blue.
(c) In a neutralisation reaction, an acid and a base form salt and water.
(d) Litmus, a natural indicator, is extracted from lichen.
(e) The reaction between hydrochloric acid and sodium hydroxide produces sodium chloride as one of the products.

Mark ‘T’ if the statement is true and ‘F’ if it is false-

(a) Acids and bases are corrosive in nature. (T)
(b) Litmus is a synthetic indicator. (F)
(c) Phenolphthalein turns pink in basic solutions. (T)
(d) Factory wastes are usually neutralised with acids. (F)

Tick (✓) mark the correct answer in each of the following-

(a) Which of the following is a natural indicator?
- (ii) Litmus ✓
(b) Hydrochloric acid reacts with sodium hydroxide to form-
- (ii) Sodium chloride ✓

Match the items of Column I with those given in Column II-

(a) Acids – (ii) Are corrosive
(b) Bases – (iv) Feel slippery
(c) Neutralisation – (iii) Form salt and water
(d) Litmus – (i) Turns red in acidic solutions

What is the role of neutralisation in environmental protection, particularly regarding factory waste?

Neutralisation is crucial in environmental protection as it helps in treating acidic or basic factory wastes, making them safe for disposal and preventing harm to the environment and water bodies.

How does the pH of soil affect plant growth, and what measures are taken to maintain the right pH balance?

The pH of the soil affects nutrient availability and plant growth. Acidic or overly basic soils can hinder plant growth. Lime is often added to acidic soils to increase the pH, while sulphur or aluminium sulphate can be used to lower the pH of alkaline soils.

Explain the difference in properties between acidic and basic salts.

Acidic salts result from the partial neutralisation of a strong acid with a weak base and tend to have acidic properties. Basic salts form from the neutralisation of a strong base with a weak acid and exhibit basic characteristics.

Why are substances like baking soda and vinegar commonly used in household cleaning?

Baking soda (a base) and vinegar (an acid) are common in cleaning due to their ability to neutralise odours (through neutralisation reactions) and their effectiveness in breaking down grime and dirt.

Describe the safety measures that should be taken while handling acids and bases.

Wear protective gear like gloves and goggles, work in a well-ventilated area, avoid direct skin contact, and always add acid to water, not water to acid, to prevent splashing and exothermic reactions.

Discuss the use of acids and bases in food preservation and cooking, providing specific examples.

Acids like vinegar and citric acid are used in food preservation for their antimicrobial properties. Bases like sodium bicarbonate (baking soda) are used in cooking, particularly in baking, to help dough rise.

Match the items of Column I with suitable items in Column II-

(a) Citric acid – (iii) Aerated drinks
(b) Sodium hydroxide – (i) Manufacture of soaps
(c) Vinegar – (ii) Food preservation
(d) Calcium hydroxide – (iv) Baking powder

Also Check – Rapid Revision – Class 7 Science – Chapter 5-Acids, Bases and Salts

Worksheet 2 -Acids, Bases and Salts – Student Worksheet (Unsolved)

Fill in the blanks-

(a) Acids are substances with a __________ taste, while bases have a __________ taste and __________ texture.
(b) A natural indicator used to test acids and bases is __________, which is obtained from __________.
(c) When acids react with bases, a __________ reaction occurs, producing __________ and __________.
(d) The pH scale ranges from __________ (most acidic) to __________ (most basic), with __________ being neutral.
(e) To neutralise an acid in a case of indigestion, one might use a base like __________.

Mark ‘T’ if the statement is true and ‘F’ if it is false-

(a) Acids can be stored in metal containers. (T/F)
(b) Bases have a soapy texture. (T/F)
(c) Turmeric changes colour in acidic solutions. (T/F)
(d) Acid rain is beneficial for plant growth. (T/F)

Tick (✓) mark the correct answer in each of the following-

(a) Hydrochloric acid turns blue litmus paper-
- (i) Blue (ii) Red (iii) No change (iv) Green
(b) In a neutralisation reaction, the pH of the resulting solution is usually-
- (i) Below 7 (ii) Above 7 (iii) Around 7 (iv) Unchanged

Match the items of Column I with those given in Column II-

Column I

(a) Hydrochloric acid
(b) Sodium hydroxide
(c) Phenolphthalein in acid
(d) Neutralization reaction

Column II

(i) Base
(ii) Acid
(iii) Produces salt and water
(iv) Turns colourless

What is the environmental impact of acid rain, and how is it formed?

Discuss why acids are not stored in metal containers but in glass containers.

Explain the importance of the pH scale in everyday life.

How does neutralisation play a role in treating indigestion? Give an example of a substance used.

Describe the effect of using a base to treat an ant bite and the reason behind it.

Explain the process and importance of neutralising factory wastes before disposal.

Match the items of Column I with suitable items in Column II-

Column I

(a) Litmus in acidic solution
(b) Calcium hydroxide
(c) Acid rain
(d) Neutral pH

Column II

(i) Turns red
(ii) Has a pH of 7
(iii) Damages buildings and vegetation
(iv) Used in soil treatment

Class 7 – Chapter 4- Acids, Bases, and Salts- An Overview of Activities

Worksheet 2 -Acids, Bases and Salts – Solved Worksheet

Fill in the blanks-

(a) Acids are substances with a sour taste, while bases have a bitter taste and soapy texture.
(b) A natural indicator used to test acids and bases is litmus, which is obtained from lichens.
(c) When acids react with bases, a neutralisation reaction occurs, producing salt and water.
(d) The pH scale ranges from 1 (most acidic) to 14 (most basic), with 7 being neutral.
(e) To neutralise an acid in a case of indigestion, one might use a base like milk of magnesia.

Mark ‘T’ if the statement is true and ‘F’ if it is false-

(a) Acids can be stored in metal containers. (F)
(b) Bases have a soapy texture. (T)
(c) Turmeric changes colour in acidic solutions. (F)
(d) Acid rain is beneficial for plant growth. (F)

Tick (✓) mark the correct answer in each of the following-

(a) Hydrochloric acid turns blue litmus paper-
- (ii) Red ✓
(b) In a neutralisation reaction, the pH of the resulting solution is usually-
- (iii) Around 7 ✓

Match the items of Column I with those given in Column II-

(a) Hydrochloric acid – (ii) Acid
(b) Sodium hydroxide – (i) Base
(c) Phenolphthalein in acid – (iv) Turns colourless
(d) Neutralization reaction – (iii) Produces salt and water

What is the environmental impact of acid rain, and how is it formed?

Acid rain, formed from pollutants like sulphur dioxide and nitrogen oxides reacting with rainwater, severely affects vegetation, animal life, and buildings.

Discuss why acids are not stored in metal containers but in glass containers.

Acids are stored in glass containers because they are reactive and can corrode metal containers, whereas glass is inert and does not react with acids.

Explain the importance of the pH scale in everyday life.

The pH scale helps in determining the acidity or basicity of a substance, which is crucial in various fields like chemistry, medicine, agriculture, and environmental science.

How does neutralisation play a role in treating indigestion? Give an example of a substance used.

Neutralization plays a role in treating indigestion by using bases (like milk of magnesia) to neutralise excess stomach acid.

Describe the effect of using a base to treat an ant bite and the reason behind it.

A base like baking soda neutralises the formic acid injected by an ant bite, alleviating irritation and pain.

Explain the process and importance of neutralising factory wastes before disposal.

Neutralising acidic factory wastes with bases before disposal is essential to prevent environmental pollution and protect aquatic life.

Match the items of Column I with suitable items in Column II-

(a) Litmus in acidic solution – (i) Turns red
(b) Calcium hydroxide – (iv) Used in soil treatment
(c) Acid rain – (iii) Damages buildings and vegetation
(d) Neutral pH – (ii) Has a pH of 7

Also Check – Class 7 science -Chapter 5-Acids, Bases and Salts- Complete Notes

Worksheet 3 -Acids, Bases and Salts – Student Worksheet (Unsolved)

Fill in the blanks-
- (a) Acids are substances that taste __________, and bases taste __________ and feel __________.
- (b) A common natural indicator used to identify acids and bases is __________, which turns __________ in acidic solutions and __________ in basic solutions.
- (c) In the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH), the products formed are __________ and __________.
- (d) Acid rain contains high levels of __________, __________, and __________ acids, which can damage __________ and __________.
- (e) Neutralization in everyday life can be observed in __________ for indigestion and __________ treatment for acidic or basic soil.
Mark ‘T’ if the statement is true and ‘F’ if it is false-
- (a) Litmus paper is a synthetic indicator. (T/F)
- (b) Bases feel soapy to the touch. (T/F)
- (c) Acid rain is beneficial for the environment. (T/F)
- (d) Neutralization reactions always produce a neutral salt. (T/F)
Tick (✓) mark the correct answer in each of the following-
- (a) The pH value of a neutral solution is-
  - (i) 0 (ii) 7 (iii) 14
- (b) Phenolphthalein turns __________ in a basic solution-
  - (i) Red (ii) Blue (iii) Colourless
Match the items of Column I with those given in Column II-
- Column I
  - (a) Citric Acid
  - (b) Sodium Hydroxide
  - (c) Vinegar
  - (d) Neutralization
- Column II
  - (i) Found in lemons and oranges
  - (ii) Used in soap making
  - (iii) Contains acetic acid
  - (iv) Reaction between an acid and a base
Why is it important to neutralise factory wastes before they are discharged into water bodies?
Describe the role of neutralisation in treating ant bites.
Explain the impact of acid rain on buildings and monuments.
What are the consequences of excessive use of chemical fertilisers on soil pH?
How can soil acidity be corrected for better plant growth?
Discuss the importance of pH in maintaining a healthy digestive system.
Match the items of Column I with suitable items in Column II-

Column I
- (a) Hydrochloric acid
- (b) Magnesium hydroxide
- (c) Quicklime
- (d) Turmeric indicator
Column II
- (i) Neutralizes stomach acid
- (ii) Turns red in basic solutions
- (iii) Used to neutralise acidic soil
- (iv) Present in gastric juices

Also Check – Class 7 science -Chapter 5-Acids, Bases and Salts –Definition and Explanation of Important Keywords

Worksheet 3 -Acids, Bases and Salts – Solved Worksheet

Fill in the blanks-

(a) Acids are substances that taste sour, and bases taste bitter and feel soapy.
(b) A common natural indicator used to identify acids and bases is litmus, which turns red in acidic solutions and blue in basic solutions.
(c) In the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH), the products formed are sodium chloride (NaCl) and water (H2O).
(d) Acid rain contains high levels of carbonic, sulphuric, and nitric acids, which can damage buildings and vegetation.
(e) Neutralization in everyday life can be observed in antacids for indigestion and soil treatment for acidic or basic soil.

Mark ‘T’ if the statement is true and ‘F’ if it is false-

(a) Litmus paper is a synthetic indicator. (F)
(b) Bases feel soapy to the touch. (T)
(c) Acid rain is beneficial for the environment. (F)
(d) Neutralization reactions always produce a neutral salt. (F)

Tick (✓) mark the correct answer in each of the following-

(a) The pH value of a neutral solution is-
- (ii) 7 ✓
(b) Phenolphthalein turns pink in a basic solution-
- (i) Red

Match the items of Column I with those given in Column II-

(a) Citric Acid – (i) Found in lemons and oranges
(b) Sodium Hydroxide – (ii) Used in soap making
(c) Vinegar – (iii) Contains acetic acid
(d) Neutralization – (iv) Reaction between an acid and a base

Why is it important to neutralise factory wastes before they are discharged into water bodies?

It’s important to neutralise factory wastes to prevent the acids in them from harming aquatic life and polluting water bodies.

Describe the role of neutralisation in treating ant bites.

Neutralisation is used to counteract the acidic formic acid in ant stings with a mild base like baking soda, alleviating pain and irritation.

Explain the impact of acid rain on buildings and monuments.

Acid rain, containing sulfuric and nitric acids, can corrode and damage the surfaces of buildings and monuments, especially those made of marble.

What are the consequences of excessive use of chemical fertilisers on soil pH?

Excessive use of chemical fertilisers can make the soil too acidic, which can negatively affect plant growth and soil health.

How can soil acidity be corrected for better plant growth?

Soil acidity can be corrected by adding bases like quicklime or slaked lime, which neutralise the excess acid in the soil.

Discuss the importance of pH in maintaining a healthy digestive system.

A balanced pH is crucial in the digestive system, particularly in the stomach, where a specific level of acidity is needed to digest food effectively.

Match the items of Column I with suitable items in Column II-

(a) Hydrochloric acid – (iv) Present in gastric juices
(b) Magnesium hydroxide – (i) Neutralizes stomach acid
(c) Quicklime – (iii) Used to neutralise acidic soil
(d) Turmeric indicator – (ii) Turns red in basic solutions

Also Check – Acid Rain – Class 7 -Chapter 5-Acids, Bases and Salts

Worksheet 4 -Acids, Bases and Salts – Student Worksheet (Unsolved)

Fill in the blanks-

(a) Acids are derived from the Latin word “acere,” meaning __________, and have a __________ taste.
(b) Examples of natural acids include __________ and __________.
(c) Bases usually taste __________ and feel __________ when touched.
(d) An example of a base commonly found in homes is __________.
(e) A natural indicator that changes colour in the presence of acids and bases is __________.

Mark ‘T’ if the statement is true and ‘F’ if it is false-

(a) Citric acid is found in citrus fruits like oranges and lemons. (T/F)
(b) Acetic acid is present in baking soda. (T/F)
(c) Turmeric changes colour in basic solutions. (T/F)
(d) Litmus is a synthetic indicator. (T/F)

Tick (✓) mark the correct answer in each of the following-

(a) Formic acid is produced by-
- (i) Orange trees (ii) Ants (iii) Apples (iv) Grapes
(b) Sodium bicarbonate is naturally found in-
- (i) Mineral springs (ii) Citrus fruits (iii) Ant stings (iv) Milk

Match the items of Column I with those given in Column II-

Column I	Column II
(a) Lactic Acid	(i) Found in curd (yoghourt)
(b) Calcium Hydroxide	(ii) Naturally formed when limestone is heated
(c) Ascorbic Acid	(iii) Vitamin C, present in many fruits
(d) Ammonium	(iv) Produced by decomposition of organic matter

Why is it not advisable to identify substances as acids or bases using taste?

What is the role of indicators like litmus and turmeric in identifying acids and bases?

Describe the practical application of acids and bases in everyday life, providing two examples.

Explain the importance of natural indicators in determining the acidity or basicity of substances.

Discuss the environmental implications of acid rain.

Explain how neutralisation reactions are used in treating indigestion and ant bites.

Also Check – NCERT Solutions For Class 7 Science Chapter 5 – Acids, Bases and Salts

Worksheet 4 -Acids, Bases and Salts – Solved Worksheet

Fill in the blanks-

(a) Acids are derived from the Latin word “acere,” meaning sharp, and have a sour taste.
(b) Examples of natural acids include citric acid (found in citrus fruits) and ascorbic acid (Vitamin C in fruits).
(c) Bases usually taste bitter and feel slippery when touched.
(d) An example of a base commonly found in homes is baking soda (sodium bicarbonate).
(e) A natural indicator that changes colour in the presence of acids and bases is litmus.

Mark ‘T’ if the statement is true and ‘F’ if it is false-

(a) Citric acid is found in citrus fruits like oranges and lemons. (T)
(b) Acetic acid is present in baking soda. (F) – Acetic acid is found in vinegar.
(c) Turmeric changes colour in basic solutions. (T)
(d) Litmus is a synthetic indicator. (F) – Litmus is a natural indicator.

Tick (✓) mark the correct answer in each of the following-

(a) Formic acid is produced by-
- (ii) Ants ✓
(b) Sodium bicarbonate is naturally found in-
- (i) Mineral springs ✓

Match the items of Column I with those given in Column II-

(a) Lactic Acid – (i) Found in curd (yoghourt)
(b) Calcium Hydroxide – (ii) Naturally formed when limestone is heated
(c) Ascorbic Acid – (iii) Vitamin C, present in many fruits
(d) Ammonium – (iv) Produced by decomposition of organic matter

Why is it not advisable to identify substances as acids or bases using taste?

Tasting chemicals to identify them is dangerous as many acids and bases are corrosive and can cause harm if ingested. It’s important to use safe methods like pH testing or indicators for identification.

What is the role of indicators like litmus and turmeric in identifying acids and bases?

Indicators like litmus and turmeric change colour in the presence of acids or bases, which helps in identifying the nature of a substance without the need for hazardous taste tests. These indicators provide a visual means to determine the acidity or basicity of a substance.

Describe the practical application of acids and bases in everyday life, providing two examples.

Acids and bases are widely used in daily life. For example, vinegar (acetic acid) is used in cooking and as a cleaning agent, while baking soda (a base) is used in baking and as a mild cleaning agent.

Explain the importance of natural indicators in determining the acidity or basicity of substances.

Natural indicators are important because they provide a simple, cost-effective, and environmentally friendly way to determine the acidity or basicity of substances. They are especially useful in educational settings and situations where sophisticated laboratory equipment is not available.

Discuss the environmental implications of acid rain.

Acid rain, caused by pollutants like sulphur dioxide and nitrogen oxides in the atmosphere, can have devastating effects on the environment. It damages forests, harms aquatic life in lakes and rivers, and corrodes buildings and monuments.

Explain how neutralisation reactions are used in treating indigestion and ant bites.

Neutralisation reactions are used in treating indigestion by using antacids (which are bases) to neutralise excess stomach acid. For ant bites, which contain formic acid, applying a mild base like baking soda can neutralise the acid and reduce pain and irritation.

Also Check – What is Neutralisation? – The Basics Explained

Also Check – Indicators for Acid and Base- A Guide for Students

Also Check – Chapter 5- Acids, Bases and Salts-Class 7 Question and Answer (Long)

Also Check – Chapter 5- Acids, Bases and Salts-Class 7 Question and Answer (MCQ)

Also Check – Chapter 5- Acids, Bases and Salts-Class 7 Question and Answer (Fill in the Blanks)

Also Check – Chapter 5- Acids, Bases and Salts-Class 7 Question and Answer (Short)