SEBA Class 7 Science Chapter 5 Acids, Bases, and Salts – Textbook Solutions & MCQ (Part I)
Get Class 7 Science Chapter 5 “Acids, Bases, and Salts” Solutions for SEBA Assam (English Medium) students. This chapter, from Part I of the Science book, explains the properties of acids and bases, indicators used to test pH, neutralization reactions, and the formation of salts. Our solutions provide detailed NCERT/SCERT textbook answers, important MCQs, and key explanations to help students understand how acids and bases interact in chemical reactions and their importance in daily life. These solutions are structured to make learning easy and effective for exam preparation.
Class 7 Science
Chapter – 5 (Part I) Ospin Academy
Acids, Bases and Salts
EXERCISE
Q. 1. State differences between acids and bases.
Ans:
|
Acids |
Bases |
|---|---|
|
1. Acids have sour taste. |
1. Bases have bitter taste. |
|
2. Acids are not soapy to touch. |
2. Bases feel soapy to touch. |
|
3. Acids turn blue litmus to red. |
3. Bases turn red litmus to blue. |
Q. 2. Ammonia is found in many household products, such as window cleaners. It turns red litmus blue, what is its nature?
Ans: Basic.
Q. 3. Name the source from which litmus solution is obtained. What is the use of this solution?
Ans: Litmus solution is extracted from lichens. It is used to determine the given solution is acidic or basic.
Q. 4. Is the distilled water acidic/basic/ neutral? How would you verify it?
Ans: The distilled water is neutral. Put a drop of the distilled water on a strip of the red litmus paper with the help of a dropper. We observe that colour of the litmus paper is not change.
The solutions which do not change the color of either red or blue litmus are known as neutral solutions. These substances are neither acidic nor basic.
Q. 5. Describe the process of neutralization with the help of an example.
Ans: The process due to which an acid completely reacts with a base to form salt and water as the only products is called neutralization.
Acid + Base → Salt + Water
Example: Hydrochloric acid (HCI) + Sodium hydroxide (NaOH)
Sodium chloride (NaCl)+ Water (H₂O)
Q. 6. Make T if the statement is true and ‘F” if it is false.
(i) Nitric acid turns red litmus blue.
Ans: F.
(ii) Sodium hydroxide turns blue litmus red.
Ans: F.
(iii) Sodium hydroxide and hydrochloric acid neutralize each other and form salt and water.
Ans: T.
(iv) Indicator is a substance which shows different colors in acidic and basic solutions.
Ans: T.
Q.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 one wants neutral drink. How will Dorji decide which drink is to be served to whom?
Ans: Dorji can decide with the help of litmus paper:
(i) The drink which would turn a red litmus blue would be basic.
(ii) If the drink turns a blue litmus to red would be acidic.
(iii) The drink which would not affect both red and blue litmus would be neutral.
Q. 8. Example, why?
(a) An antacid tablet is taken when you suffer from acidity.
Ans: (a) Our stomach contains hydrochloric acid. It helps us to digest food. But too much of acid in the stomach causes indigestion.
Sometimes indigestion is painful. To relieve indigestion, we take an antacid such as milk of magnesia, which contains magnesium hydroxide. It neutralizes the effect of excessive acid.
(b) Calamine solution is applied on the skin when an ant bites.
Ans: The sting of an ant contains formic acid. When an ant bites, it injects the acidic liquid into the skin. The effect of the sting can be neutralized by rubbing moist baking soda (sodium hydrogen carbonate) or calamine solution, which contains zinc carbonate.
(c) Factory waste is neutralized before disposing it into the water bodies.
Ans: The wastes of many factories contain acids. If they are allowed to flow into the water bodies, the acids will kill fish and other organisms. The factory wastes are, therefore, neutralized by adding basic substances.
Q. 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:
|
Name of the liquid |
Effect on turmeric paper |
|---|---|
|
(i) Hydrochloric acid |
Yellow to blue |
|
(ii) Sodium hydroxide |
Yellow to red |
|
(iii) Sugar solution |
No change |
Q. 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 is neutral, because the solutions which do not change the color of either red or blue litmus are known as neutral solution. These substances are neither acidic nor basic.
Q. 11. Consider the following statements:
(a) Acids and bases both change colour of all indicators.
(b) If an indicator gives a color 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: (ii) a and b.
FAQs – Class 7 Science Chapter 5 (Acids, Bases, and Salts, SEBA Assam)
Q1: What are acids and bases?
Acids are substances that release hydrogen ions (H⁺) in water, while bases release hydroxide ions (OH⁻).
Q2: What are indicators used for in acids and bases?
Indicators like litmus paper, turmeric, China rose, and phenolphthalein are used to identify whether a substance is acidic, basic, or neutral.
Q3: What is neutralization?
Neutralization is a chemical reaction in which an acid reacts with a base to form salt and water, reducing their effects.
Q4: Where can I find Class 7 Science Chapter 5 solutions for SEBA Assam?
You can find detailed textbook solutions, MCQs, and explanations for SEBA Assam Class 7 Science Chapter 5 on this page.
Q5: Where can I find solutions for all Class 7 Science chapters?
To get solutions for all Class 7 Science chapters, Click Here
