NCERT Solutions for Class 7 Science Chapter 5 Acids, Bases and Salts
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Chapter 5 Nutrition in Animals Class 7 Science NCERT Questions and Answers help students grasp basic concepts better and faster. Students can cross check their answers and also whether they learned it properly or not. It will allow students to cover the entire syllabus effectively without any frustration. You can pinpoint your weaknesses and prepare accordingly to change it in a positive way.
NCERT Solutions for Class 7 Science Chapter 5 Acids, Bases and Salts
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| Study Material for Class 7 Science Chapter 5 Acids, Bases and Salts |
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Page No: 56
Exercises
1. State differences between acids and bases.
Answer
| Acids | Bases |
| (i) Acids are sour in taste. | (i) Bases are bitter in taste. |
| (ii) It turns litmus paper red. | (ii) It turns litmus paper blue. |
| (iii) It doesn't change the colour of turmeric indicator. | (iii) It changes the colour of turmeric indicator to red. |
| (iv) It doesn't feel soapy on touching. | (iv) It feels soapy on touching. |
2. Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?
Answer
Ammonia turns red litmus blue so it is basic in nature.
3. Name the source from which litmus solution is obtained. What is the use of this solution?
Answer
Litmus solution is obtained from lichens dissolved in distilled water.
It is used to detect the acidic and basic characteristic of a substance as it changes its colour to red in acidic medium and into blue in basic medium.
4. Is the distilled water acidic/basic/neutral? How would you verify it?
Answer
The distilled water is neutral.
Litmus paper can be used to verify whether the distilled water acidic/basic/neutral.
Distilled water doesn't changes the colour of blue or red litmus paper. So, it is neutral in nature.
5. Describe the process of neutralisation with the help of an example.
Answer
When an acid solution and a base solution are mixed in suitable amounts both the solutions
neutralise the effect of each other and a new substance salt is formed. This process is called neutralisation.
When the solution of sodium hydroxide (a base) and hydrochloric acid (an acid) is mixed in test tube in proper ratio, both neutralize each other. In this reaction, a new substance sodium chloride is formed. The mixture obtain is neutral in nature which can be justified by litmus solution or phenolphthalein solution.
The reaction can be written as:
Hydrochloric acid(HCl) + Sodium hydroxide(NaOH) → Sodium Chloride(NaCl) + Water (H2O)
6. 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 neutralise each other and form salt and water. (T/F)
(iv) Indicator is a substance which shows different colours in acidic and basic solutions. (T/F)
(v) Tooth decay is caused by the presence of a base. (T/F)
Answer
(i) F
(ii) F
(iii) T
(iv) T
(v) F
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?
Answer
Dorji will take red and blue litmus paper and dip it into every bottles of soft drink. The drink in which red litmus paper turnes blue is bottle of basic drink. The drink in which blue litmus paper turns red is bottle of acidic drink.The drink in which both litmus paper show no changes in colour is of neutral drink.
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.
Answer
(a) Excessive amount of acids in stomach causes pain and antacids prove relief from that pain. Antacids neutralises the effect of excessive acid as it is a base and acts against the acids.
(b) When an ant bites, it injects the acidic liquid (formic acid) into the skin. Calamine solution contains zinc carbonate which neutralises the effect of acid injected by the ant.
(c) Factory waste is neutralised before disposing it into the water bodies because these wastes contain chemicals and harmful acids which may be harmful for the aquatic life and also its leads to pollution of water.
Page No: 57
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.
Answer
Dip the turmeric indicator in each liquids. The liquid in which the colour of turmeric indicator changes to red is basic in nature i.e. sodium hydroxide. Since, we already identified sodium hydroxide. We will pour the sodium hydroxide in other two bottles. The liquid which get warm after pouring the sodium hydroxide(base) in it is of hydrochloric acid as heat gets evolved in the neutralisation process. The last one which shows no effect is liquid of sugar solution.
10. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
Answer
The above solution could be a base or a neutral solution because blue litmus paper doesn't change its colour in the neutral as well as basic solution.
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.
(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
(i) All four
(ii) a and d
(iii) b and c
(iv) only d
Answer
(iv) only d
Go Back To NCERT Solutions for Class 7 Science
Chapter 5 Acids, Bases and Salts Class 7 Science NCERT Solutions
Chapter 5 Class 7 Science NCERT Questions and Answers will improve application skills and clear your confusions. These are helpful in building a great foundation of concepts and make easy for the students to understand basics. Students will develop the ability to identify what improvements and changes need to be made. It will help in developing a wider body of knowledge when you’re brainstorming a solution.
Class 7 Science Chapter 5 Acids, Bases and Salts NCERT Questions and Answers - Topics
• Acids And Bases
• Natural Indicators Around Us
→ Litmus: A natural dye
→ Turmeric is another natural indicator
→ China Rose as Indicator
• Neutralisation
• Neutralisation In Everyday Life
→ Indigestion
→ Ant bite
→ Soil treatment
→ Factory wastes
Class 7 Science Chapter 5 Acids, Bases and Salts NCERT Questions and Answers - Notes
• The taste of acid is sour. There are many substances that contain acid and so taste sour. For example, lemon, curd, pickles, orange juice, vinegar, etc.
• Substances that taste sour and are corrosive in nature are called acids. The chemical nature of such a substance is known as acidic.
• The substances like baking soda which are bitter in taste and feel soapy on touching are known as bases. The nature of such substances is said to be basic.
• Special type of substances are used to test whether a substance is acidic or basic. These substances are known as indicators.
→ The indicators change their colour when added to a solution containing an acidic or a basic substance. Turmeric, litmus, China rose petals (Gudhal), etc., are some of the naturally occurring indicators.
• The most commonly used natural indicator is litmus. It is extracted from lichens. It has a mauve (purple) colour in distilled water. When added to an acidic solution, it turns red and when added to a basic solution, it turns blue.
→ Generally, it is available as red and blue litmus paper
• The solutions which do not change the colour of either red or blue litmus are known as neutral solutions.
• Turmeric changes colour to indicate acidic and basic substances. In an acidic medium, it remains yellow, while in a basic medium, it turns reddish-brown.
• A solution of china rose turns green in a basic solution and bright pink or magenta in an acidic solution.
• The reaction between an acid and a base is known as neutralisation. Salt and water are produced in this process with the evolution of heat.
• The stomach contains hydrochloric acid, which helps in the digestion of food. To relieve indigestion, we take an antacid such as milk of magnesia, which contains magnesium hydroxide which neutralises the effect of excessive acid.
• When an ant bites, it injects the acidic liquid (formic acid) into the skin. The effect of the acid can be neutralised by rubbing moist baking soda (sodium hydrogencarbonate) or calamine solution, which contains zinc carbonate.
• The stomach contains hydrochloric acid, which helps in the digestion of food. When the soil is too acidic, it is treated with bases like quick lime (calcium oxide) or slaked lime (calcium hydroxide). If the soil is basic, organic matter (compost) is added to it. Organic matter releases acids which neutralises the basic nature of the soil.
• The wastes of many factories contain acids. The factory wastes are, therefore, neutralised by adding basic substances.
Chapter 4 Heat Class 7 Science Questions and Answers - MCQ Questions with answers
1. Acid present in soured curd is:
(a) Lactic acid
(b) Acetic acid
(c) Tartaric acid
(d) Oxalic acid
► (a) Lactic acid
2. Which of the following acid is used by gold smith for dissolving gold?
(a) Nitric acid
(b) Sulphuric acid
(c) Aqua Regia
(d) Hydrochloric acid
► (c) Aqua Regia
3. In case of indigestion, we use:
(a) Antacids
(b) Antibiotic
(c) Alcohols
(d) Antipyretic
► (a) Antacids
4. Acid present in vinegar is:
(a) formic acid
(b) acetic acid
(c) sulphuric acid
(d) nitric acid
► (b) acetic acid
5. Which of the following is a natural indicator?
(a) Turmeric
(b) Methyl orange
(c) Oxalic acid
(d) Phenolphthalein
► (a) Turmeric
6. Sodium chloride turns
(a) Methyl orange yellow
(b) Blue litmus red
(c) No change in colour
(d) Red litmus blue
► (c) No change in colour
7. All acids contain:
(a) Oxygen
(b) Nitrogen
(c) Hydrogen
(d) Carbon
► (c) Hydrogen
8. Vitamin C is the another name of
(a) Tartaric acid
(b) Citric acid
(c) Acetic acid
(d) Ascorbic acid
► (d) Ascorbic acid
9. Which of the following is acidic in nature?
(a) Apple juice
(b) Soap solution
(c) Slaked lime
(d) None of the above
► (a) Apple juice
10. Dry HCl gas do not change the colour of dry litmus paper because
(a) Hydrogen gas is evolved only in presence of water
(b) Hydrogen ion is produced in aqueous condition
(c) Acids shows acidic property due to water
(d) Water provide acidic characters
► (b) Hydrogen ion is produced in aqueous condition
NCERT Solutions for Science prepared by our experts try to provide all round clarity of questions. Through these NCERT Solutions, students should not waste time and adopt a strategy that helps them operate and learn at maximum efficiency. This NCERT Solutions for 7 Science are helpful resources that can help you not only cover the entire syllabus but also provide in depth analysis of the topics.