Ch.30 – Assertion and reason :- Exercise 1


Directions : Choose the correct alternatives from the following options as given below for the Assertion (A) and Reason (R), given in each of the questions.

(a) Both (A) and (R) are true and (R) is the correct explanation of A.

(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).

(c) (A) is true but (R) is false.

(d) (A) is false but (R) is true.

(e) Both (A) and (R) are false.

1. Assertion (A): When common salt is kept open, it absorbs moisture from the air.

Reason (R): Common salt contains magnesium chloride.

Answer & Solution
1 (a) Common salt contains magnesium chloride, hence absorbs moisture from the air. Hence, both (A) and (R) are true and (R) is the correct explanation of (A).

2. Assertion (A): The steam engine was invented by James Watt.

Reason (R) : There was a problem of taking out -, water from flooded mines.

Answer & Solution
2 (c) Assertion is correct but Reason is false.

3. Assertion (A) : We prefer to wear white clothes in winter.

     Reason (R) : White clothes are good reflectors of heat.

Answer & Solution
3 (d) We prefer dark clothes in winter as they absorb heat and keep us warm, hence Assertion (A) is not correct. But, Reason (R) is correct as white clothes reflect the heat.

4. Assertion (A): Earthworms are not good for agriculture.

    Reason (R) : Earthworms break down the soil into fine particles and make it soft.

Answer & Solution
4 (d) Earthworms make the soil fertile, hence Assertion is false and Reason is true.

5. Assertion (A) : Mercury is the farthest planet from the sun.

    Reason (R): Mercury is the smallest planet in the entire solar-system .

Answer & Solution
5 (d) Mercury is the smallest planet, but it is not the farthest planet. Hence, the correct answer is (d).

6. Assertion (A): Red green colour blindness 0ccurs with more frequency in males than in females.

    Reason (R) : Females have two chromosomes and males have one .

Answer & Solution
6 (a) Both the Assertion and Reason are correct.

7. Assertion (A): Indus Valley people knew the art of navigation.

    Reason (R) : Indus Valley seals indicate prevalence of overseas trade.

Answer & Solution
7 (d) Indus Valley people knew the art of navigation but the Reason that the seals of that time indicate prevalence of overseas trade is false. Hence, the correct answer is (d).

8. Assertion (A) : A person with blood group 0 positive is supposed to be a universal recipient.

    Reason (R) : The blood type 0 positive does not contain any antigens.

Answer & Solution
8 (e) Both Assertion and Reason are false because the person with blood group O-positive is the universal blood donor and similarly, O-positive blood group contains antigens.

9. Assertion (A) : Noise pollution is an unwanted accumulation of noise in the atmosphere.

    Reason (R) : It interferes with the communication.

Answer & Solution
9 (a) Noise pollution interferes with communication, hence is an unwanted accumulation of noise in the atmosphere.

10. Assertion (A) : Akbar found Din-e-Illahi

      Reason (R) : He was motivated by self glorification.

Answer & Solution
10 (c) Assertion is correct because Din-e-Illahi was founded by Akbar but the Reason is false.

11. Assertion (A): Safety fuses are made up of materials having a high melting point.

     Reason (R) : Safety fuses should be resistant to electric current.

Answer & Solution
11(e) Safety fuses are made up of metals having low melting points to avoid any accident in case of short-circuit. Also the safety fuses should not be resistant to electric current.

12. Assertion (A) : Milk production in India is low as compared to other countries of the world.

       Reason (R) : The animal rearers in India are poor.

Answer & Solution
12 (c) Milk production in India is low as compared to other countries of the world, is true. But, the Reason is false.

13. Assertion (A): Sprouting should not be done before consuming the grains.

       Reason (R) : Sprouting kills many vital vitamins.

Answer & Solution
13 (e) Both Assertion and Reason are false because sprouted grains are used to increase the nutrient content of the grains.

14. Assertion (A) : The Goitre is a common disease in mountainous regions.

       Reason (R) : The diet of the people in mountains lacks content.

Answer & Solution
14 (a) Goitre is a common disease in the people residing in mountainous region, because the diet taken by them lacks in iodine. Hence, Assertion (A) is true but Reason (R) is false.

15. Assertion (A): Roughaes prevents constipation.

      Reason (R) : Roughaes add bulk to the food.

Answer & Solution
15 (a) Roughages add bulk to the food, hence make the food easier to be digested and thus prevent constipation.

16. Assertion (A): Diamond is used for cutting glass.

      Reason (R) : Diamond has a high refractive index.

Answer & Solution
16 (b) Assertion is correct because diamond being a very hard substance, is used to cut glass. However, the reason is false.

17. Assertion (A): India is a democratic country.

      Reason (R) : India has a Constitution of its own.

Answer & Solution
17 (b)Both Assertion and Reason are correct, but India is a democratic country because the Government is elected by its citizen and not because .India has its own Constitution.

18. Assertion (A) : Neptune is the coldest planet.

      Reason (R) : It receives slanting rays of the sun.

Answer & Solution
18 (c) Neptune is the farthest planet from the sun, and hence is the coldest planet. However, the Reason is false.

19. Assertion (A): Food materials should not be soaked in water for a long time.

       Reason (R) : Washing leads to loss of vitamin A and vitamin D from the foodstuff.

Answer & Solution
19 (c) Food materials should not be soaked in water for a long time because it leads to loss of vitamins. However, the Reason is false.

20. Assertion (A) : Water kept in earthen pots gets cooled in summer.

       Reason (R) : Evaporation causes cooling.

Answer & Solution
20 (a) Earthen pots let the water evaporate through their pores, and hence keep the water cool.

21. Assertion (A): In the upper courses, the main work of the river is erosion.

      Reason (R) : River flows swiftly in their upper courses.

Answer & Solution
21 (a) In its upper course, the river rushes down a steep slope, and hence flows swiftly causing erosion.

22. Assertion (A): Most of the ancient civilisations grew near the rivers.

Reason (R) : The main occupation of man was agriculture.

Answer & Solution
22 (b) The Assertions is correct because most of the ancient civilisations grew near the rivers as land over there was fertile and water was easily available. But, the Reason is not the correct explanation of the Assertion.

23. Assertion (A) : Telephone wires sag more in summer.

Reason (R) : They expand due to summer heat.

Answer & Solution
23 (a) Both the Assertion and Reason are correct as due to heat in summer, wires get loose.

24. Assertion (A) : The body of the shes is streamlined.

       Reason (R) : The streamlined body helps the fish to cut its way through the water.

Answer & Solution
24 (a) Yes, stream-lined bodies help the fishes to cut their ways through the water.

25. Assertion (A): Seeds should be treated with fungicide solution.

Reason (R): Seeds do not germinate, unless treated with fungicide solution.

Answer & Solution
25 (c) Seeds are treated with fungicides before sowing to avoid seed born diseases. But, it is not a true fact tha unless seeds are treated with fungicide solution, they cannot germinate.

 Directions for Q. No. 26 to 30: Each of the question below has a set of Assertion (A) and Reason (R). Mark your answer as:

(a) if both A and R are true and R is the correct explanation of A

(b) A is true but R is false

(c) if both A and R are true but R is not the correct explanation of A .

(d) A is false but R is true

26. Assertion (A): India has a tropical monsoon type climate.

Reason (R): India is located exactly between the tropical latitudes.

Answer & Solution
Ans.(C)

27. Assertion (A): For the production of aluminium, cheap electricity is essential.

Reason (R): Extraction of aluminium from its ore requires abundant supply of electricity.

Answer & Solution
Ans.(C)

28. Assertion (A) : Winds are deflected to their right in Northern Hemisphere and to the left in the Southern                                                  Hemisphere.

Reason (R) : Rotation of earth causes the changes in wind direction.

Answer & Solution
Ans.(B)

29. Assertion (A): Noise pollution is an unwanted accumulation of noise in the atmosphere.

Reason (R) : It interferes with communication.

Answer & Solution
Ans.(C)

30. Assertion (A) : Forest cutting is undesirable from the point of view of soil erosion.

Reason (R) : Cutting of forests reduces the percolation of rain water

Answer & Solution
Ans.(A)