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By Maitree Choube
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Updated on 18 Jun 2025, 13:36 IST
Science helps us understand how the world around us works, from the food we eat to the substances we use daily. Class 7 Science Chapter 4 Acids, Bases and Salts introduces students to some of the most important chemical substances in everyday life.
With the help of Class 7 Acids Bases and Salts NCERT Solutions, students will learn how to identify acids and bases, understand their properties, and recognize neutralization reactions.
These NCERT Class 7 Science Chapter 4 Acid Base and Salts solutions are designed to make learning easier and more interactive. By using these Acid Base and Salt Class 7 notes, students can clear their doubts, prepare better for exams, and build a strong foundation in chemistry. Each topic question and answer follows the CBSE 2025–26 syllabus, making it perfect for quick revision and concept clarity.
Chapter 4 – Acids, Bases and Salts in Class 7 Science introduces students to some of the most important types of substances used in daily life and industries. With the help of NCERT solutions Acids Bases and Salts Class 7, students will understand what acids and bases are, how to identify them, and how they react to form salts. This chapter builds the foundation for higher-level chemistry.
Infinity Learn provides complete and well-structured NCERT Class 7 Science Chapter 4 Acids Bases and Salts solutions as per the latest CBSE syllabus. These solutions explain every concept in a simple and easy-to-understand way. They also help students practice Class 7 Acids Bases and Salts questions and answers effectively for better exam preparation.
Students looking for easy and reliable revision can now access the acids bases and salts Class 7 questions and answers PDF download to study offline. This resource covers every important concept from the textbook in a simple and clear format.
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Whether you need Class 7th Science Chapter 4 Acids Bases and Salts question answer for homework or quick exam prep, this PDF has it all. Download the acids, bases and salts Class 7 questions and answers PDF to boost your understanding and score better in science exams.
1. State differences between acids and bases.
| S.No. | Acids | Bases |
| 1 | They are sour in taste | They are bitter in taste |
| 2 | They turn blue litmus to red | They turn red litmus to blue |
| 3 | Generally acids give H+ ions when they are dissolved in water. Examples: Hydrochloric acid (HCl), Sulphuric acid (H2SO4), Nitric acid (HNO3) | Generally bases give OH– ions when they are dissolved in water. Examples: Sodium Hydroxide (NaOH), Ammonium Hydroxide (NH4OH), Calcium Hydroxide [Ca(OH)2] |
2. Ammonia is found in many house hold products, such as window cleaners. It turns red litmus to blue. What is its nature?
Ans: Ammonia turns red litmus to blue due to its basic nature.
3. Name the source from which litmus solution is obtained. What is the use of this solution ?
Ans: 1) Litmus solution is extracted from lichens.
2) It has a mauve (purple) colour in distilled water.
3) When added to an acidic solution, it turns Purple to Red.
4) When added to a basic solution, it turns Purple to Blue.
5) It is available in the form of a solution, (or) in the form of strips of paper known as litmus paper.
4. Is the distilled water acidic / basic / neutral ? How would you verify it ?
Ans: 1) The distilled water is neutral.
2) Put a drop of distilled water on the strips of red and blue litmus papers, each with the help of a dropper.
3) We observe that colour of the litmus paper is not changed.
4) Water is neither acidic nor basic i.e., water is neutral.
5. Describe the process of neutralisation with the help of an example.
Ans: 1) The reaction between an acid and a base is known as neutralisation.
2) Salt and water are produced in this process with the evolution of heat.
Acid + Base; Salt + Water
(Heat is evolved)
Ex : Hydrochloric acid + Sodium Hydroxide Sodium chloride + Water
HCl + NaOH; NaCl + H2O
6. Mark 'T' if the statement is true and 'F' if it is false.
Ans :
| S.No. | Statement | True/False |
| 1 | Nitric acid turns red litmus blue | False |
| 2 | Sodium hydroxide turns blue litmus red | False |
| 3 | Sodium hydroxide and Hydrochloric acid neutralise each other and form salt and water | True |
| 4 | Indicator is a substance which shows different colour in acidic and basic solutions | True |
| 5 | Tooth decay is caused by the presence of a base | False |
7. Dorji has a few bottles of soft drink in his restaurant. But unfortunately, these are not labelled. He has to serve the drinks on the demand of customers. One customer wants acidic drink, another wants basic and third wants neutral drink. How will Dorji decide which drink is to be served to whom ?
Ans:
8. Explain why :
a. An antacid tablet is taken when you suffer from acidity.
b. Calamine solution is applied on the skin when an ant bites.
Ans:
1) The sting of an ant contains Formic acid.
2) When an ant bites, it injects acidic liquid into the skin i.e, Formic acid.
3) The effect of the acid can be neutralised by rubbing moist baking soda (Sodium hydrogen
carbonate) or Calamine solution, Which contains Zinc carbonate.
c. Factory waste is neutralised before disposing it into the water bodies.
Ans :
1) The wastes of many factories contain acids.
2) If they are allowed to flow into the water bodies those acids will kill fish and other organisms
3) There fore the factory wastes are neutralised by adding basic substances.
9. Three liquids are given to you. One is Hydrochloric acid, another is Sodium hydroxide and third is a sugar solution. How will you identify them ? You have only turmeric indicator ?
Ans: Turmeric is a natural indicator present in yellow colour. In acidic medium it remains same, where as in basic medium turns to reddish brown colour.
When we dip turmeric indicator into three test tubes containing HCl, NaOH and Sugar solution, in which test tube it turns to reddish brown it is NaOH. Then use the same Indicator and dip in remaining two solutions, in which test tube it turns back to yellow it is HCl and the remaining solution is sugar solution.
10. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution ? Explain.
Ans: The nature of the solution may be neutral or basic because the solutions which do not change the colour of blue litmus, are either neutral or basic.
11. Consider the following statements.
a) Both acids and bases change colour of all indicators.
b) If an indicator gives a colour change with an acid, it does not give a change with a base.
c) If an indicator changes colour with a base, it does not change colour with an acid.
d) Change of colour in an acid and a base depends on the type of the indicator.
Which of these statements are correct ?
i) All four ii) a and b iii) b and c iv) only d
Ans: iv) only d
Students can easily revise using these Acid Bases and Salts Class 7 questions and answers, which provide step-by-step explanations, diagrams, and real-life examples to strengthen understanding. The NCERT solutions make complex concepts easy and help students gain confidence in science.
Infinity Learn’s NCERT solutions Acids Bases and Salts Class 7 are designed to help students fully understand this important chemistry chapter. The solutions break down each concept simply, making science more engaging and easier to revise. Here are the top benefits tailored specifically to Class 7 Science Chapter 4 Acids, Bases and Salts:
Chapter-Specific Benefits:
The chemical formula of common salt is NaCl, which stands for sodium chloride. It is made of sodium (Na⁺) and chloride (Cl⁻) ions.
Acids, bases, and salts are types of chemical compounds. They are formed through different reactions between elements and have distinct properties and uses.
Acids:
Bases:
Salts:
These are key parts of acids bases and salts Class 7 questions and answers.
Acids: Substances that taste sour and turn blue litmus red; they release H⁺ ions in water.
Bases: Bitter in taste, slippery to touch, and turn red litmus blue; they release OH⁻ ions in water.
Salts: Formed when an acid reacts with a base (neutralization); they contain a metal ion from the base and a non-metal ion from the acid.
These are core concepts covered in NCERT Class 7 Science Chapter 4 acids bases and salts solutions.
These solutions are based on the latest CBSE syllabus and include step-by-step explanations. They guide students on how to write accurate, well-structured answers during exams.
Yes, students can download acids bases and salts Class 7 questions and answers PDF from Infinity Learn Website. We provide chapter wise pdf for all classes and subjects.