21. Assertion :- Plastic is not toxic when come in contact with food and medicines.
Reason :- Plastics are used world-over because they are safe for packaging of foods, medicines and child care products.
22. Assertion :- Thermosetting plastics can not be remoulded.
Reason :- (R) Thermosetting plastics can be softened on heating.
23. Assertion :- Nylon fibres can not be used for making ropes for climbers.
Reason :- Nylon fibres are very strong fibres.
24. Assertion :- Malleability is the property of metals due to which they can be beaten into thin sheets.
Reason :- Aluminium is a metal and hence possesses malleability property.
25. Assertion :- When a copper vessel is exposed to moist air for long, it acquires a dull green coating.
Reason :- Metals can react with air and moisture.
26. Assertion :- Metals react with acids to form respective salts along with evolution of hydrogen gas that burns with a pop sound.
Reason :- There are some metals like copper, silver, gold and platinum that do not liberate hydrogen with acids.
27. Assertion :- Pesticides are the chemicals used to kill pest.
Reason :- Pests are the insects or rodents that destroy much of our crop yield.
28. Assertion :- The cutting of the crop after it is mature is called harvesting.
Reason :- The harvested grains, usually are stored in huge stores, after they
are’ properly dried in sunlight. Such stores are called granaries.
29. Assertion :- The process of separation of grains from the chaff in the
harvested plant is called threshing.
Reason :- The tool used traditionally for sowing seeds is thresher.
30. Assertion :- Crop rotation ensures that the same crop will not grow
continuously and lead to the erosion of the soil fertility.
Reason :- By growing crops that require different sets of nutrient, we can
ensure the soil fertility is restored.
Answers
Answer:
21 Assertion is false but Reason is true
22 Both are correct and it is the correct explanation
23 Both are correct but not correct explanation
24 Both are correct and it is the correct explanation
25 Both are correct and it is the correct explanation
26 Both are correct but not correct explanation
27 Both are correct and it is the correct explanation
28 Both are correct but not correct explanation
29 Both are correct but not correct explanation
30 Both are correct and it is the correct explanation
21. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(Plastics are not reactive, costs less and more durable than other materials used for manufacturing storage items.)
22. Assertion is true but Reason is false.
(Thermosets cannot be recycled. This is because their constituent polymers are crosslinked and strong and they cannot be recycled.)
23. Assertion is false and Reason is true.
(A thin strand of nylon fibre is said to be stronger than a steel wire. Due to its strength, it is used for making climbing ropes.)
24. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(The reason provided is not directly linked to assertion.)
25. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(Copper is a metal and mostly all metals react with air and moisture. This is the reason why copper gets a dull green coating when exposed to air for a long time.)
26. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(The reason provided is not directly linked to assertion.)
27. Both Assertion and Reason are true and Reason is the correct explanation of assertion.
(Pests are the organisms that harm crops and they are killed using pesticides.)
28. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(The reason provided is not directly linked to assertion.)
29. Assertion is true but Reason is false.
(The traditional tool for sowing seeds is seed drill.)
30. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(Crop rotation is the planting pattern which ensures that the soil fertility is retained and not completely depleted due to continuous usage by crops.)