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Class 7 Science MCQ Question of Acids, Bases and Salts with Answers?

Answer 1

Students can get here Class 7 Science MCQ Questions of Acids, Bases and Salts with Answers based on NCERT Text book for Class 7. Science Class 7 MCQ Questions of Acids, Bases and Salts are very helpful to score high marks in board exams. MCQ Questions for Class 10 Science with Answers was Prepared Based on Latest Exam Pattern. Know your preparation level on MCQ Questions with Answers. 

Here we have covered Important Questions on Acids, Bases and Salts for Class 7 Science. If you practiced properly. You also get idea about the type of questions and method to answer in your Class 7 examinations. Students can solve Class 10 Science Acids Bases and Salts Multiple Choice Questions with Answers to know their preparation level. You can also verify your answers from our provided International Business 1 Class 11 MCQ Questions with Answers.

Practice MCQ Questions for Class 7 Science

1. An oxide is acidic and has a pungent odour. It could be

(a) sulphur dioxide 
(b) carbon dioxide
(c) sodium oxide
(d) nitrogen dioxide

2. Out of these gases which one is used in fire extinguishers

(a) CO₂
(b) SO₂
(c) NO₂
(d) H₂S 

3. 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

4. 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

5. Turmeric is a natural indicator. On adding its paste to acid and base separately, which colours would be observed.

(a) Yellow in both acid and base
(b) Yellow in acid and red in base
(c) Pink in acid and yellow in base
(d) Red in acid and blue in base

6. 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

7. 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

8. Which of the following set of substances contain acids?

(a) Grapes, lime water
(b) Vinegar, soap
(c) Curd, milk of magnesia
(d) Curd, vinegar

9. 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

10. Which of the following is an acid-base indicator?

(a) Vinegar
(b) Lime water
(c) Turmeric
(d) Baking soda

11. Which of the following is not a indicator?

(a) Phenolphthalein
(b) Methyl orange
(c) Litmus
(d) Methyl chloride

12. When CO₂ gas is passed through lime water, it turns milky. Which of the following compounds is responsible for this milkiness ?

(a) Calcium oxide
(b) Calcium chloride
(c) sodium carbonate
(d) Calcium carbonate

13. The reaction in which an acid react with a base to form salt and water is called as

(a) Addition reaction
(b) Displacement reaction
(c) Neutralisation reaction
(d) Substitution reaction

14. Which of the following ion is responsible for the acidic nature of hydrochloric acid ?

(a) Hydrogen ion
(b) Hydroxide ion
(c) Chloride ion
(d) Hydrochloride ion

15. Acid present in soured curd is

(a) Lactic acid
(b) Acetic acid
(c) Tartaric acid
(d) Oxalic add

16.  Distilled water is:

(a) acidic
(b) basic
(c) neutral
(d) none of these

17. Ammonia that turns red litmus blue is:

(a) acidic
(b) basic
(c) neutral
(d) none of these

18. An antacid tablet is given to a person when he suffers from:

(a) obesity
(b) acidity
(c) dog bite
(d) none of these

19. Ant’s bite injects:

(a) acetic acid
(b) formic acid
(c) hydrochloric acid
(d) none of these

20. Litmus is extracted from

(a) curd
(b) grapes
(c) lichens
(d) cabbage

21.Acid used in eye wash is

(a) carbonic acid
(b) acetic acid
(c) benzoic acid
(d) boric acid

22. Magnesium hydroxide is found in:

(a) soap
(b) lime water
(c) milk of magnesia
(d) vegetable

23. Calcium hydroxide is found in

(a) window cleaner
(b) lime water
(c) soap
(d) lime juice

24. Acid present in cold drinks (soft drinks) is

(a) Carbonic acid
(b) Citric acid
(c) Tartaric acid
(d) Sulphuric acid

25. Which of the following is a strong Base?

(a) Copper hydroxide
(b) Sodium hydroxide
(c) Iron hydroxide
(d) Calcium oxide

Answer 2

1. Answer: (d) nitrogen dioxide

Explanation: Nitrogen dioxide is non- metallic oxide hence it is acidic in nature and it has a pungent odour.

2. Answer: (a) CO₂

Explanation: Three types of extinguishing agents are typically used—carbon dioxide, dry chemical, and foam water for fires involving flammable liquids, greases, and oils. Carbon dioxide is a compressed gas agent that prevents combustion by displacing the oxygen in the air surrounding the fire.

3. Answer: (b) add acid to water

Explanation:When we add water to acid, it releases some amount of energy. We can feel this energy by touching the surface of the test tube. Sometimes, released heat is too huge, because of this glasses of test tube may break down and acid can split over. So, in practice, you have to take an excessive amount of water and mix acid drop by drop. In this way, heat generated can be cooled down by this water and mistakes can be prevented.

4. Answer: (c) a salt and water

Explanation:The product of a neutralisation reaction is salt and water. 

For example, hydrochloric acid reacts with sodium hydroxide to form sodium chloride salt and water. 

5.  Answer: (b) Yellow in acid and red in base

Explanation: Turmeric compound is a naturally occurring yellow color compound. It is an acid-base indicator, it remains yellow when acidic or neutral solutions are added to it.

6. Answer: (d) colourless and pink

Explanation: Phenolphthalein is a synthetic indicator and is weakly acidic in nature. When it is added to an acidic solution, it turns colourless. In the basic solution, it appears pink in colour.Phenolphthalein is colourless in acidic solution and pink in basic solution.

7. Answer: (a) Organic matter

Explanation: To improve quality and reduce the basic nature of the soil, the organic matter must be added to the soil. Organic matter releases acids that can neutralize the base of the soil and hence the quality of soil can be improved.

8. Answer: (d) Curd, vinegar

Explanation: Curd contains lactic acid and vinegar contains acetic acid. Lime water, soap and milk of magnesia are basic substances and grapes contains tartaric acid.

9. Answer: (c) Either acidic or neutral

Explanation: Phenolphthalein gives pink colour in basic solution. It remains colourless in acidic or neutral solution.Phenolphthalein only gives colour in basic medium.

10. Answer: (c) Turmeric

Explanation: Turmeric compound is a naturally occurring yellow colour compound. It is an acid-base indicator, turmeric compound remains yellow when acid or neutral solutions are added to it.

11.  Answer: (d) Methyl chloride

Explanation: Methyl chloride cannot act as an indicator because it does not show any colour change in acidic or basic medium whereas methyl orange, phenolphthalein and turmeric are well-known indicators.

12. Answer: (d) Calcium carbonate 

Explanation: Lime water is calcium hydroxide and when carbon dioxide is passed it reacts with calcium hydroxide to form calcium carbonate which turns lime water milky.

13. Answer: (c) Neutralisation reaction

Explanation: The reaction between acid and base produces salt and water, which is the example of neutralization reaction.

14. Answer: (a) Hydrogen ion

Explanation: The presence of hydrogen ions |H⁺| imparts acidic nature to HCl.

15. Answer: (a) Lactic acid

Explanation: Lactic Acid or milk acid is an organic acid with chemical formula C₃H₆O₃. When milk sugar or lactose undergoes fermentation, the product obtained is lactic acid. It is found in cottage cheese, leban, sour milk, yogurt, and Koumiss.

16. Answer: (c) neutral

Explanation: Distilled water is neutral in character, i.e. it is neither acidic nor basic. Neutral nature of distilled water can be verified by the use of blue and red litmus paper.

17. Answer: (b) basic

Explanation: Ammonia turns red litmus to blue so it is basic in nature.

18. Answer: (b) acidity

Explanation: We take an antacid such as milk of magnesia to neutalises the excessive acid released in stomach.

19. Answer: (b) formic acid

Explanation: Formic acid, a component of ant venom uncommon in bee or wasp stings, is derived from the superfamily name Formicidae.

20. Answer: (c) lichens

Explanation: Litmus, mixture of coloured organic compounds obtained from several species of lichens that grow in the Netherlands, particularly Lecanora tartarea and Roccella tinctorum.

21.Answer: (d) boric acid

Explanation: Boric acid is often an ingredient in eye wash products. It's predominantly used as a mild antiseptic and to maintain the pH of the eye wash solution.

22. Answer: (c) milk of magnesia

Explanation: Magnesium hydroxide is an ingredient in OTC products, such as Milk of Magnesia. It also draws water into the intestines to help soften stool and encourage a bowel movement.

23. Answer: (b) lime water

Explanation: solutions of calcium hydroxide in water is known as lime water. Hence, Calcium Hydroxide {Ca(OH)₂} is found in lime water.

24. Answer: (a) Carbonic acid

Explanation: Carbonic acid is added to soft drinks to make it fizzy. When the bottle is opened, the pressure decreases and the carbonic acid changes into carbon dioxide and water making it fizzy.

25. Answer: (b) Sodium hydroxide

Explanation: Sodium hydroxide is a strong base because it dissociates completely in an aqueous solution to form sodium cations, Na⁺, and hydroxide anions, OH⁻. Sodium hydroxide is completely ionic, containing sodium ions and hydroxide ions.

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