CBSE Class 7 Science - MCQ and Online Tests - Unit 5 - Acids, Bases and Salts

CBSE Class 7 Science – MCQ and Online Tests – Unit 5 – Acids, Bases and Salts

 

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CBSE Class 7 Science – MCQ and Online Tests – Unit 5 – Acids, Bases and Salts

Choose the correct answer:

Question 1.
Phenolphthalein is a synthetic indicator and its colours in acidic and basic solutions, respectively are:
(a) red and blue
(b) blue and red
(c) pink and colourless
(d) colourless and pink

Answer

Answer: (d) colourless and pink

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Question 2.
On adding phenolphthalein indicator to a colourless solution, no change is observed. What is the nature of this solution?
(a) Basic
(b) Either acidic or basic
(c) Either acidic or neutral
(d) Either basic or neutral

Answer

Answer: (c) Either acidic or neutral

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Question 3.
Out of these gases which one is used in fire extinguishers
(a) CO₂
(b) SO₂
(c) NO₂
(d) H₂S

Answer

Answer: (a) CO₂

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Question 4.
The correct way of making a solution of acid in water is to
(a) add water to acid
(b) add acid to water
(c) mix acid and water simultaneously
(d) add water to acid in a shallow container

Answer

Answer: (b) add acid to water

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Question 5.
Products of a neutralisation reaction are always:
(a) an acid and a base
(b) an acid and a salt
(c) a salt and water
(d) a salt and a base

Answer

Answer: (c) a salt and water

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Question 6.
An oxide is acidic and has a pungent odour. It could be
(a) sulphur dioxide
(b) carbon dioxide
(c) sodium oxide
(d) nitrogen dioxide

Answer

Answer: (d) nitrogen dioxide

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Question 7.
Phenolphthalein is a synthetic indicator and its colours in acidic and basic solutions, respectively are:
(a) red and blue
(b) blue and red
(c) pink and colourless
(d) colourless and pink

Answer

Answer: (d) colourless and pink

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Question 8.
When the soil is too basic, plants do not grow well in it. To improve its quality what must be added to the soil?
(a) Organic matter
(b) Quick lime
(c) Slaked lime
(d) Calamine solution

Answer

Answer: (a) Organic matter

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Question 9.
Which of the following set of substances contain acids?
(a) Grapes, lime water
(b) Vinegar, soap
(c) Curd, milk of magnesia
(d) Curd, vinegar

Answer

Answer: (d) Curd, vinegar

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Question 10.
On adding phenolphthalein indicator to a colourless solution, no change is observed. What is the nature of this solution?
(a) Basic
(b) Either acidic or basic
(c) Either acidic or neutral
(d) Either basic or neutral

Answer

Answer: (c) Either acidic or neutral

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Question 11.
Which of the following is an acid-base indicator?
(a) Vinegar
(b) Lime water
(c) Turmeric
(d) Baking soda

Answer

Answer: (c) Turmeric

 

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