Class 7 chemistry important questions with answers are provided here for Chapter 5 – Acids, Bases and Salts. These important questions are based on the CBSE board curriculum and correspond to the most recent Class 7 chemistry syllabus. By practising these Class 7 important questions, students will be able to quickly review all of the ideas covered in the chapter and prepare for the Class 7 annual examinations.
Download Class 7 Chemistry Chapter 5 – Acids, Bases and Salts Important Questions with Answers PDF by clicking on the button below.
Class 7 Chapter 5 – Acids, Bases and Salts Important Questions with Answers
Multiple Choice Type Questions
Q1. What is the chemical name of baking soda?
(a) Sodium acetate
(b) Sodium bicarbonate
(c) Sodium sulphate
(d) None of the above
Answer: (b) Sodium bicarbonate
Explanation: Sodium bicarbonate is the chemical name of baking soda.
Q2. Baking soda turns _____.
(a) Blue litmus red
(b) Red litmus blue
(c) Both (a) and (b)
(d) None of the above
Answer: (a) Blue litmus red
Explanation: Baking soda is acidic in nature. Therefore, it turns blue litmus paper red.
Q3. Which of the following substances turns a red litmus blue?
(a) Acidic
(b) Basic
(c) Both (a) and (b)
(d) None of the above
Answer: (b) Basic
Explanation: A base turns red litmus paper blue.
Q4. Which of the following substances turns a blue litmus red?
(a) Acidic
(b) Basic
(c) Both (a) and (b)
(d) None of the above
Answer: (a) Acidic
Explanation: An acid turns a blue litmus red.
Q5. A base has _______.
(a) A bitter taste
(b) A sour taste
(c) Both (a) and (b)
(d) None of the above
Answer: (a) A bitter taste
Explanation: A base has a bitter taste.
Q6. An acid has _______.
(a) A bitter taste
(b) A sour taste
(c) Both (a) and (b)
(d) None of the above
Answer: (b) A sour taste
Explanation: An acid has a sour taste.
Q7. Which of the following is not an indicator?
(a) Methyl orange
(b) Antacid pill
(c) Both (a) and (b)
(d) None of the above
Answer: (b) Antacid pill
Explanation: Antacid pill is used to relieve excess acid in the stomach. It is basic in nature.
True or False Type Questions
Q1. Nitric acid turns red litmus paper blue.
Answer: False
Explanation: Nitric acid is naturally acidic and turns blue litmus paper red. Thus, it does not turn red litmus paper blue. So, the above statement is false.
Q2. Sodium hydroxide turns blue litmus red.
Answer: False
Explanation: Sodium hydroxide is basic in nature and turns red litmus paper blue. Thus, it does not turn blue litmus red. So, the above statement is false.
Q3. Sodium hydroxide reacts with ammonia to form salt and water.
Answer: False
Explanation: Sodium hydroxide reacts with an acid to form salt and water. Ammonia is a base, and two bases can not react together to give a neutralisation reaction. So, the above statement is false.
Q4. An indicator is a substance which gives different colours with acidic and basic solutions.
Answer: True
Explanation: The indicator is a substance that shows a colour change when brought in contact with an acid, base or neutral substance. Thus, the above statement is true.
Q5. An antacid is acidic in nature.
Answer: False
Explanation: An antacid is used to relieve excess acid in the stomach. It is basic in nature. Thus, the above statement is false.
Q6. Acetic acid is present in vinegar.
Answer: True
Explanation: Vinegar is the solution of 4 to 6 per cent of acetic acid in water. Thus, the above statement is true.
Q7. Sodium hydroxide reacts with hydrochloric acid to form sodium chloride and water.
Answer: True
Explanation: Sodium hydroxide reacts with hydrochloric acid to give a neutralisation reaction forming salt and water.
Fill in the blanks Type Questions
Q1. Mineral acids are _____ acids.
Answer: Laboratory
Q2. Grapes contain _____ acid while apples contain _____ acid.
Answer: Tartaric, malic
Q3. Bases are _____ to touch.
Answer: Soapy
Q4. When you use methyl orange as an indicator, it gives _____ colour for acids.
Answer: Red
Q5. The acids such as hydrochloric acid, sulphuric acid and nitric acid are known as ______ acid.
Answer: Mineral
Q6. Excessive use of fertilisers in the field makes the soil ______.
Answer: Unfertile
Q7. Phenolphthalein, litmus paper and methyl orange are known as _______.
Answer: Indicator
Q8. The substance that tastes sour and turns blue litmus red is known as _______.
Answer: Acid
Q9. The substance that tastes bitter and turns red litmus blue is known as _______.
Answer: Base
Q10. The substance formed from a neutralisation reaction between an acid and a base is _____ and _____.
Answer: Salt and water
Q11. The substance which turns red litmus blue is known as ______.
Answer: Base
Q12. The substance which turns blue litmus red is known as ______.
Answer: Acid
Match the following Type Questions
Q1. Match the items of column A with those of column B.
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Q2. Match the items of column A with those of column B.
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Very Short Answer Type Questions
Q1. Name any three strong acids.
Answer:
Sulphuric acid, Nitric acid and hydrochloric acid are strong acids.
Q2. Name any three strong bases.
Answer:
Sodium hydroxide, potassium hydroxide, and lithium hydroxide are strong bases.
Q3. Name any three weak acids.
Answer:
Citric acid, phosphoric acid, and lactic acid are weak acids.
Q4. Name any three weak bases.
Answer:
Ammonium hydroxide, ferric hydroxide, and zinc hydroxide are weak bases.
Q5. Name the acid present in the car batteries.
Answer:
Sulphuric acid is present in car batteries.
Q6. Name a neutral salt. Give its one application.
Answer:
Sodium chloride is a neutral salt. It is also known as common salt and is added to food items.
Q7. What is salt?
Answer:
Salt is the product formed when an acid reacts with a base, i.e. neutralisation reaction.
Q8. Name any three acids found in fruits.
Answer:
Malic acid, tartaric acid and ascorbic acid are found in fruits.
Q9. Name any two acid-base indicators.
Answer:
Litmus and phenolphthalein are the two acid-base indicators.
Q10. What are acids and bases?
Answer:
An acid is a sour substance that turns blue litmus red. In contrast, a base is a bitter substance that feels soapy to the touch and turns red litmus blue.
Q11. What is the pH scale?
Answer:
The pH scale is used to measure the strength of acids and bases.
Q12. Why are antacids used to cure acidity?
Answer:
Antacids are used to cure acidity as they neutralise the excessive acid released in the stomach.
Q13. What is the chemical name of the milk of magnesia?
Answer:
The chemical name of the milk of magnesia is magnesium hydroxide.
Q14. Name any two antacids.
Answer:
Milk of magnesia and sodium bicarbonate are antacids.
Short Answer Type Questions
Q1. What are the causes of indigestion?
Answer:
Indigestion is caused by acidity, which in turn is caused due to the excess secretion of hydrochloric acid in the human stomach.
Q2. What is acid rain?
Answer:
Rainwater dissolves pollutants like carbon dioxide, nitrogen dioxide, and sulphur dioxide to form carbonic acid, nitric acid, and sulphuric acid. Acid rain is any form of precipitation that includes acidic components, such as carbonic acid, nitric acid, and sulphuric acid, that fall to the ground from the atmosphere.
Q3. What is the use of litmus paper? What is the natural colour of litmus paper?
Answer:
Litmus paper is used as one of the chemical indicators. It is used to determine whether a solution is acidic or basic. The natural colour of litmus is purple. If the blue litmus paper is put in an acidic solution, it turns red.
Q4. What happens when a drop of dilute sulphuric acid is added to the china rose indicator?
Answer:
When a drop of dilute sulphuric acid is added to the china rose indicator, it will turn the light pink colour of the china rose indicator to magenta.
Q5. What happens when a china rose indicator is added to acid and base?
Answer:
China rose indicator turns magenta in an acidic medium and green in a basic medium.
Q6. Why does a farmer add quicklime in the field?
Answer:
Soil gets acidic due to chemicals and fertilisers or acid rain. Farmer adds quicklime in the field as it helps in neutralising the soil’s acidity.
Q7. Name the chemicals added to the acidic soil to make it neutral.
Answer: Calcium and magnesium carbonate are added to the acidic soil to make it neutral.
Q8. Why is toothpaste alkaline?
Answer:
Toothpaste is alkaline because the bacteria in our mouth break down the food and release acids. To neutralise this acidic effect, we brush our teeth with toothpaste. For neutralising acids, toothpaste is basic or alkaline in nature.
Q9. How can you cure an ant sting?
Answer:
We can use calamine solution on the ant bites as ant injects formic acid into the skin on biting, which causes inflammation, to the skin. We can neutralise the effect of the acid by rubbing calamine. Calamine solution contains zinc carbonate, a fragile base that causes no skin harm.
Q10. How can you prepare the china rose indicator?
Answer:
China rose indicator can be prepared by soaking some petals of china rose in warm water for a couple of hours. The red-coloured solution is used as an indicator for detecting an acid, base, or neutral solution.
Q11. What are an indicator and a universal indicator?
Answer:
An indicator is a substance that shows a colour change when brought in contact with an acid, base or neutral substance. In contrast, a universal indicator is a mixture of indicators which gives different colours for different pH values, thus helping to measure the strength of a substance.
Long Answer Type Questions
Q1. What happens when a base is treated with
(a) Red litmus
(b) Blue litmus
(c) China rose indicator
(d) Turmeric indicator
Answer:
(a) A base turns red litmus blue.
(b) A base will not affect blue litmus.
(c) A base will turn the light ink colour of the china rose indicator to green.
(d) A base will turn the turmeric indicator red.
Q2. What happens when an acid is treated with
(a) Red litmus
(b) Blue litmus
(c) China rose indicator
(d) Turmeric indicator
Answer:
(a) An acid will not affect red litmus.
(b) An acid turns blue litmus red.
(c) An acid will turn the light pink colour of the china rose indicator to magenta or bright pink.
(d) An acid will not affect the turmeric indicator.
Q3. Why should we treat factory wastes before discharging them into water bodies?
Answer:
We should treat factory wastes before releasing them into water bodies, as factory wastes contain acids which, if untreated and discharged into water bodies, will cause harm to fish and other aquatic organisms living in water bodies. Therefore, they should be treated with essential substances to neutralise and then discharged into water bodies.
Q4. Answer the following questions.
(a) Why does a turmeric stain on a white shirt turn red when it is washed with soap?
(b) What happens when acid and bases are treated with china rose indicator?
Answer:
(a) Turmeric is a natural indicator which changes its yellow colour into reddish brown when it comes in contact with a solution of base. Hence, when soap (which is basic) is scrubbed on the stain, the stain turns red.
(b) China rose indicator turns magenta in an acidic medium and green in a basic medium.
Q5. Answer the following questions.
(a) What happens when acidic soil is treated with purple cabbage juice?
(b) What is soil treatment?
Answer:
(a) When acidic soil is treated with purple cabbage juice, it will turn red. It is a great indicator and a test for acidity or alkaline soil.
(b) Soil treatment is the process in which contaminated soil, which cannot grow crops, is treated to recycle and make it usable for agriculture or any other purpose.
Q6. When we mix equal parts of acid and base, a reaction takes place.
(a) What is the name of the reaction?
(b) What product is formed?
Answer: If an equal amount of acidic and basic substances are mixed, then
(a) The name of the reaction is the neutralisation reaction.
(b) The product formed is salt and water.
Q7. Differentiate between acids and bases.
Answer:
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Sl. No. |
Acid |
Base |
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1. |
Acids are sour in taste. |
Bases are bitter in taste. |
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2. |
Acids turn blue litmus paper into red colour. |
The base does not change the colour of the blue litmus paper. |
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3. |
Acids do not change the colour of the red litmus. |
Bases turn red litmus paper to blue colour. |
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4. |
Acids do not change the colour of turmeric. |
Bases turn turmeric into red colour. |
Read Also:
- Acids and Bases
- Acids, Bases and Salts
- General Properties of Acids and Bases
- Acids and Bases Questions
- Chemistry Worksheets Class 7 on Chapter 5 Acids, Bases and Salts with Answers – Set 1
- Chemistry Worksheets Class 7 on Chapter 5 Acids, Bases and Salts with Answers – Set 2
- Chemistry Worksheets Class 7 on Chapter 5 Acids, Bases and Salts with Answers – Set 3
- Chemistry Concept Questions and Answers
- Class 7 Chemistry Chapter 5 Acids, Bases and Salts MCQs
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