NCERT Solutions for Class 7 Science Chapter 5 Acid Base and Salt

Learn from School Connect Online in this chapter we will learn about Acids, bases and salts which are the three important groups of chemical substances that are used by us in different ways. Some of the acids, bases and salts occur in nature and they can be made artificially in factories also.NCERT Solutions for Class 7 Science Chapter 5 Acid Base and Salt

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NCERT Solutions Download Class 7Chapter NameNCERT Solutions Download Class 7Chapter Name
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NCERT Solutions for Class 7 Chapter 2 Nutrition in AnimalsNutrition in AnimalsNCERT Solutions for Class 7 Chapter 11 Transportation in Animals and PlantsTransportation in Animals and Plants
NCERT Solutions for Class 7 Chapter 3 Fibre to FabricFibre to FabricNCERT Solutions for Class 7 Chapter 12 Transportation in Animals and PlantsReproduction in Plants
NCERT Solutions for Class 7 Chapter 4 HeatHeatNCERT Solutions for Class 7 Chapter 13 Motion and TimesMotion and Times
NCERT Solutions for Class 7 Chapter 5 Acids,Bases and SaltsAcids,Bases and SaltsNCERT Solutions for Class 7 Chapter 14 Electric Current and its EffectsElectric Current and its Effects
NCERT Solutions for Class 7 Chapter 6 Physical and Chemical ChangesPhysical and Chemical ChangesNCERT Solutions for Class 7 Chapter 15 LightLight
NCERT Solutions for Class 7 Chapter 7Weather,Climate and Adaptations of Animals to ClimateNCERT Solutions for Class 7 Chapter 16 Water;A precious resourceWater;A precious resource
NCERT Solutions for Class 7 Chapter 8Winds Storms and CyclonesNCERT Solutions for Class 7 Chapter 17 Forests;Our life lineForests;Our life line
NCERT Solutions for Class 7 Chapter 9SoilNCERT Solutions for Class 7 Chapter 18 Waste water storyWaste water story

NCERT Solutions for Class 7 Science Chapter 5 Acid Base and Salt

Exercise Questions

1. State differences between acids and bases.

Solution:

AcidsBases
Acids are sour in tasteBases are bitter in taste
Acids turn blue litmus paper into red colorThe base does not change the colour of blue litmus paper
Acids does not change the colour of the red litmusBases turn red litmus paper to blue color
Acids do not change the colour of turmericBases turn turmeric to red

2. Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?

Solution:

The answer is basic in nature

3. Name the source from which litmus solution is obtained. What is the use of this solution?

Solution:

Litmus solution is extracted from lichens. Litmus solution is used as an indicator to find acidic and basic nature of a solution.

4. Is the distilled water acidic/basic/neutral? How would you verify it?

Solution:

Distilled water is neutral in nature, and this can be tested by using red and blue litmus paper. In either of the cases, colour remains unchanged.

5. Describe the process of neutralisation with the help of an example.

Solution:

Neutralisation is a reaction between an acid and a base. Here both acids and bases get neutralised For example, when sodium hydroxide (NaOH) is added to hydrochloric acid (HCl), sodium chloride (NaCl) and water (H2O) are obtained.

NaOH + HCl → NaCl + H2O + Heat

6. Mark ‘T’ if the statement is true and ‘F’ if it is false:

(i) Nitric acid turn red litmus blue. (T/F)

Sol : False

(ii) Sodium hydroxide turns blue litmus red. (T/F)

Sol : False

(iii) Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water. (T/F)

Sol : True

(iv) Indicator is a substance which shows different colours in acidic and basic solutions. (T/F)

Sol : True

(v) Tooth decay is caused by the presence of a base. (T/F)

Sol : 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 one wants neutral drink. How will Dorji decide which drink is to be served to whom?

Solution:

Dorji can taste a few drops out of soft drinks bottles, acidic solution is sour in taste, basic solution is bitter in taste, and the neutral solution has no taste. Along with tasting, Dorji can use litmus paper to test the nature of soft drinks. He should use blue litmus paper to test the acidic solution. Dorji has to put a drop of solution on blue litmus. If it turns red then the solution will be acidic in nature.

Similarly, he can use red litmus paper to test the basic solution. He has to put a drop of solution on red litmus. If it turns blue then the solution will be basic in nature.

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.

(c) Factory waste is neutralised before disposing it into the water bodies.

Solution:

  1. The antacid tablet contains a base like milk of magnesia which neutralises the acid produced in the stomach. Hence, it is used while suffering from acidity.
  2. When an ant bites, it injects formic acid inside the skin. Calamine consists of Zinc carbonate which is basic in nature. Hence calamine neutralises the effect of formic acid to bring relief for the affected person.
  3. Factory wastes are acidic in nature which may cause harm to aquatic life. Hence, they are neutralised by using a base before disposing it into the water bodies.

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.

Solution:

Add solution to a container with a turmeric indicator. If the solution is NaOH, it would turn the turmeric indicator to red. To the same container, add test solution number 2. If the added solution is sugar, the solution indicator remains unchanged because mixture of a basic and neutral solution will remain basic in nature.

Similarly, add the test solution number 3 to another container with a turmeric indicator. If the indicator changes yellow to blue then the solution will be hydrochloric acid.

10. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.

Solution:

Above solution may be neutral or basic in nature as both of them will not change the colour of the blue litmus paper.

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 d

(iii) b, c and d

(iv) only d

Solution:

Only d) is correct

CBSE Notes for Class 7 Science Free Download for All Chapters

CBSE Class 7 Science Study NotesCBSE Class 7 Science Study Notes
Nutrition in Plants Class 7 Notes Chapter 1Respiration in Organisms Class 7 Notes Chapter 10
Nutrition in Animals Class 7 Notes Chapter 2Transportation in Animals and Plants Class 7 Notes Chapter 11
Fibre to Fabric Class 7 Notes Chapter 3Reproduction in Plants Class 7 Notes Chapter 12
Heat Class 7 Notes Chapter 4Motion and Times Class 7 Notes Chapter 13
Acids,Bases and Salts Class 7 Notes Chapter 5Electric Current and its Effects Class 7 Notes Chapter 14
Physical and Chemical Changes Class 7 Notes Chapter 6Light Class 7 Notes Chapter 15
Weather,Climate and Adaptations of Animals to Climate Class 7 Notes Chapter 7Water;A precious resource Class 7 Notes Chapter 16
Winds Storms and Cyclones Class 7 Notes Chapter 8Forests;Our life line Class 7 Notes Chapter 17
Soil Class 7 Notes Chapter 9Waste water story Class 7 Notes Chapter 18

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