Class 7 chemistry MCQs with answers are provided here for Chapter 5 Acids, Bases and Salts. These MCQs are based on the CBSE board curriculum and correspond to the most recent Class 7 chemistry syllabus. By practising these Class 7 multiple choice questions, students will be able to quickly review all of the ideas covered in the chapter and prepare for the Class 7 annual examinations as well as other competitive exams.
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Class 7 Acids, Bases and Salts MCQs
Q-1: Which of the following is a base?
a) Curd
b) Vinegar
c) Amla
d) Window cleaner
Answer: d) Window cleaner
Explanation: Bases are substances that taste bitter and feel soapy to the touch. Window cleaner possesses these qualities, making it a base.
Q-2: Which of the following is the Latin word that acid is derived from?
a) Ace
b) Acere
c) Acre
d) None of the above
Answer: b) Acere
Explanation: The word acid comes from the Latin word acere, which means sour.
Q-3: Which of the following is not an indicator that occurs naturally?
a) Gudhal
b) Turmeric
c) Litmus
d) Phenolphthalein
Answer: d) Phenolphthalein
Explanation: Phenolphthalein is a synthetic indicator that is not produced in nature. Some of the naturally occurring indicators include litmus, turmeric and gudhal (China rose).
Q-4: Which one of the following fruits contains ascorbic acid?
a) Spinach
b) Grapes
c) Unripe mangoes
d) Amla
Answer: d) Amla
Explanation: Ascorbic acid is present in amla, whereas tartaric acid is present in grapes and unripe mangoes. Spinach contains oxalic acid.
Q-5: Which of the following indicators are typically found as strips?
a) China Rose
b) Turmeric
c) Litmus
d) All of the above
Answer: c) Litmus
Explanation: Litmus is the most popular natural indicator. It is marketed as “litmus paper,” which are paper strips. It typically comes in red and blue litmus paper.
Q-6: How will the addition of turmeric affect the colour of lime water?
a) The solution becomes blue in colour
b) The solution becomes red in colour
c) The solution becomes yellow in colour
d) The solution becomes pink in colour
Answer: b) The solution becomes red in colour
Explanation: Lime water is basic in nature. When added to a basic substance, the natural indicator turmeric turns red. Thus, adding turmeric causes the lime water to turn red.
Q-7: Which of the following is the outcome of a neutralisation reaction?
a) A solution
b) A salt
c) A mixture
d) A acid and base mixture
Answer: b) A salt
Explanation: New material is created during the neutralisation reaction known as salt.
Q-8: Why is organic matter added to the soil?
a) Because organic matter is basic in nature
b) Because organic matter releases acids in the soil
c) Due to the neutral nature of organic matter
d) Because organic matter is crucial for soil.
Answer: b) Because organic matter releases acids in the soil
Explanation: Organic matter (compost) is added to the soil if it is basic. Acids are released by organic matter, which balances the soil’s basic nature.
Q-9: Which of the following chemicals is present in the calamine solution?
a) Zinc hydroxide
b) Zinc carbonate
c) Zinc oxide
d) Zinc sulphate
Answer: b) Zinc carbonate
Q-10: Which of the following acids is formed when carbon dioxide is dissolved in raindrops?
a) Carbonic acid
b) Hydrochloric acid
c) Oxalic acid
d) Formic acid
Answer: a) Carbonic acid
Explanation: When carbon dioxide dissolves in raindrops, it forms carbonic acid.
CO2 + H2O → H2CO3
Q-11: What name is given to the solutions that don’t affect the colour of either the red or the blue litmus test strips?
a) Acidic solutions
b) Salt solutions
c) Basic solutions
d) Neutral solutions
Answer: d) Neutral solutions
Explanation: Neutral solutions are those that do not alter the colour of either red or blue litmus. These substances lack both acidic and basic properties.
Q-12: Which of the following solutions will cause the blue litmus to turn red?
a) Vinegar
b) Soap
c) Milk of magnesia
d) Calamine
Answer: a) Vinegar
Explanation: Blue litmus will change to red in an acidic solution. Because vinegar contains acetic acid, it will turn the blue litmus paper red. The blue litmus paper strip won’t be affected by any other solutions because they are all basic.
Q-13: What changes in colour are produced when a basic solution is combined with the China rose indicator?
a) It turns blue
b) It turns green
c) It turns dark pink
d) No change
Answer: b) It turns green
Explanation: Acidic solutions turn dark pink (magenta) when exposed to the China rose indicator, while basic solutions turn green.
Q-14: Which of the following substances can be used to soothe the discomfort brought on by wasp stings?
a) Sodium hydrogen carbonate
b) Vinegar
c) Milk of magnesia
d) Zinc carbonate
Answer: b) Vinegar
Explanation: A basic substance that is produced by wasp stings irritates the skin. Vinegar, an acidic substance, can be used to counteract the effects of the base.
Q-15: When a man with stomach pain went to the doctor, the physician identified acidity. Which of the following would be the suitable remedy for him?
a) Lemonade drink
b) Baking soda
c) Aerated drink
d) Vinegar
Answer: b) Baking soda
Explanation: Acidity is a condition that develops when there is too much acid present. Baking soda is the only base present here, which is necessary to counteract the effects of the acid. As a result, it negates the negative effects of too much acid.
Q-16: What colour change will you observe when phenolphthalein is added to an acid?
a) Pink
b) Green
c) Colourless
d) Blue
Answer: c) Colourless
Explanation: When the solution is basic, phenolphthalein gives a pink colour. On the other hand, when the solution is acidic, it remains colourless.
Q-17: Which of the following is not a characteristic of a neutralisation reaction?
a) Temperature of the reaction mixture decreases.
b) A lot of heat evolves.
c) Along with salt, water is formed.
d) Resulting salt can be acidic, basic or neutral.
Answer: a) Temperature of the reaction mixture decreases.
Explanation: A new substance is formed during the neutralisation reaction known as salt. Salt can be acidic, basic, or neutral. As a result, neutralisation can be defined as follows: The neutralisation reaction occurs when an acid and a base react. With the evolution of heat, this process produces salt and water. The heat that is released raises the temperature of the reaction mixture.
Q-18: Which of the following describes the mixture of materials that exhibits a range of colours in acidic, basic, and neutral solutions?
a) Rainbow
b) Indicators
c) Colour palette
d) None of the above
Answer: b) Indicators
Explanation: Solutions of substances that change colour in acidic, basic, and neutral environments are called indicators.
Q-19:
Assertion: SO2 is acidic in nature
Reason: A non metallic oxide reacts with a base to form salt and water.
Choose the most appropriate option:
a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
b) Both assertion and reason are true, and the reason is not the correct explanation of the assertion.
c) Assertion is true, but the reason is false.
d) Both assertion and reason are false.
Answer: a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
Explanation: A non-metallic oxide like SO2 is acidic in nature. Therefore, the assertion is a true statement.
We know that when an acid and a base interact, salt and water are created.
Acid + Base → Salt + Water
When non-metallic oxide and a base interact, salt and water are produced.
Non-metallic oxide + Base → Salt + Water
By comparing the above two reactions, we can clearly state that SO2 (a non-metallic oxide) is acidic in nature.
Consequently, the reason is also true and is the proper justification for the assertion.
Q-20: When dilute hydrochloric acid and a substance X that can be used as an antacid are combined, a gas Y is created that is used in fire extinguishers. Determine X and Y.
a) X: NaHCO3, Y: CO2
b) X: Na2CO3, Y: CO
c) X: NaHCO3, Y: CO
d) X: Na2CO3, Y: CO2
Answer: a) X: NaHCO3, Y: CO2
Explanation: NaHCO3 is an antacid. When it reacts with HCl, the following reactions take place:
NaHCO3 + HCl → NaCl + H2O + CO2
CO2 is the gas that is used in fire extinguishers.
Hence X is NaHCO3 and Y isCO2.
Read Also:
- Acids and Bases
- Chapter 7 – Acids, Bases and Salts Worksheet-Set-1
- Chapter 7 – Acids, Bases and Salts Worksheet-Set-2
- Chapter 7 – Acids, Bases and Salts Worksheet-Set-3
- Chemistry Concept Questions and Answers
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