NCERT Solutions for Class 7 Science Chapter 5 Acids, Bases and Salts are part of NCERT Solutions for Class 7 Science. Here we have given NCERT Solutions for Class 7 Science Chapter 5 Acids, Bases and Salts.
|Chapter Name||Acids, Bases and Salts|
|Number of Questions Solved||11|
NCERT Solutions for Class 7 Science Chapter 5 Acids, Bases and Salts
State differences between acids and bases.
|(i)||Acids are sour to taste.||Bases are bitter to taste.|
|(ii)||Acid turns blue litmus to red.||Base turns red litmus to blue.|
|(iii)||Acid is a substance which contains||Bases are substances which contain|
|(iv)||hydrogen ion (H+).||hydroxyl ion (OH–)|
Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?
Name the source from which litmus solution is obtained. What is the use of this solution?
The extraction of litmus solution takes place from Lichens (a symbiotic association of algae and fungi). It is used to determine whether the given solution is acidic or basic.
Is the distilled water acidic/basic/neutral? How would you verify it?
The nature of distilled water can be verified with the help of red and blue litmus paper. It shows no change with both kinds of litmus paper, so distilled water is neutral.
Describe the process of neutralization with the help of an example.
The reaction between an acid and a base is known as neutralization. Salt and water are produced in this process with the evolution of heat.
Acid + Base → Salt + Water
Heat is also evolved in this process.
The following reaction is an ,
Mark ‘T’ if the statement is True and ‘F’ if it is False:
(i) Nitric acid turn red litmus blue. (T/F)
(ii) Sodium hydroxide turns blue litmus red. (T/F)
(iii) Sodium hydroxide and hydrochloric acid neutralize each other and form salt and water. (T/F)
(iv) Indicator is a substance which shows different colors in acidic and basic solutions. (T/F)
(v) Tooth decay is caused by the presence of a base. (T/F)
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 an acidic drink, another wants basic and third one wants neutral drink. How will Doiji decide which drink is to be served to whom?
Dorji can decide with the help of litmus paper.
- The drink which would turn a blue litmus red would be acidic.
- The drink which would turn a red litmus blue would be basic.
- The drink which would not affect either red or blue litmus would be neutral.
Explain why :
(a) An antacid tablet is taken when you suffer from acidity.
(b) Calamine solution is applied on the skin where an ant bites.
(c) Factory waste is neutralised before disposing it into the water bodies.
(a) Antacids are nothing but bases. When there is an excess of acid in stomach, antacids are taken. Antacids neutralise acids and relieve us.
(b) Ant injects an acidic liquid into the skin during bite which causes the burning sensation. Calamine solution is basic in nature. It neutralizes the acid and relieves us from the pain.
(c) Factory wastes contain acids. Therefore, these wastes, when thrown directly to water bodies, harm aquatic lives. Hence, these wastes are neutralized with basic chemicals before disposing off to water bodies.
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 a turmeric indicators.
Following steps are taken to test the given liquids:
(a) Place a drop of each liquid on turmeric indicator. The solution which changes the colour of the indicator to red is basic in nature, i.e., it is sodium hydroxide.
(b) Now put a drop of sodium hydroxide on the other two liquids separately to obtain two mixtures.
(c) One by one place the drop of each mixture on turmeric indicator. The mixture that changes the colour of indicator red contains neutral sugar solution. While the mixture which does not show any colour change in the indicator contains hydrochloric acid which was neutralized on the addition of sodium hydroxide.
Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
We know that acids turn blue litmus paper red. According to the question, no colour changes of the litmus paper, it means the given solution is acidic.
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) and (c)
(iv) only (d)
(iv) only (d).
- Chapter 1 Nutrition in Plants
- Chapter 2 Nutrition in Animals
- Chapter 3 Fibre to Fabric
- Chapter 4 Heat
- Chapter 5 Acids, Bases and Salts
- Chapter 6 Physical and Chemical Changes
- Chapter 7 Weather, Climate and Adaptations of Animals to Climate
- Chapter 8 Winds, Storms and Cyclones
- Chapter 9 Soil
- Chapter 10 Respiration in Organisms
- Chapter 11 Transportation in Animals and Plants
- Chapter 12 Reproduction in Plants
- Chapter 13 Motion and Time
- Chapter 14 Electric Current and its Effects
- Chapter 15 Light
- Chapter 16 Water A Precious Resource
- Chapter 17 Forests: Our Lifeline
- Chapter 18 Wastewater Story
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