Question 1

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : Legumes revive the soil fertility. Reason (R) : Microbes in the root nodules of legumes fix the atmospheric nitrogen.

Accepted Answer

The root nodules of leguminous plants contain certain nitrogen fixing bacteria which absorb the atmospheric nitrogen and convert it into nitrogeneous compounds useful for the plants reviving soil fertility.

Question 2

Assertion(A) : Indus valley people knew the art of navigation. Reason(R) : Indus valley seals indicate prevalence of overseas trade.

Accepted Answer

The seals found at Indus valley sites gave evidance of overseas trade, which was possible only with the knowledge of art of navigation. Thus, both A and R are true & R correctly explains A.

Question 3

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : Most of the Himalayan rivers are perennial. Reason (R) : They are fed by melting snow.

Accepted Answer

Most Himalayan rivers originating in Himalayan peaks are perennial because they are fed by the melting snow throughout the year.

Question 4

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : There is no vaccine for AIDS. Resson (R) : The AIDS virus changes its genetic code

Accepted Answer

A vaccine contains the inactivated germs of the disease. But the AIDS virus changes its genetic code and so on vaccine has been invented for it.

Question 5

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion(A) : Increase in carbon dioxide would melt polar ice. Reason (R) : Global temperature would rise

Accepted Answer

The carbon dioxide envelope in earth's atmosphere traps the heat. With increase in the proportion of carbon dioxide, therefore, the global temperature would rise, thus causing the polar ice to melt

Question 6

Assertion(A) : Most of the Himalayan rivers are perennial. Reason(R) : They are fed by melting snow.

Accepted Answer

Most Himalayan rivers are perennial because they are fed by the melting snow throughout the year. Thus, both A and R are true & R correctly explains A.

Question 7

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : Carbon monoxide when inhaled causes death. Reason (R) : Carbon monoxide combines with haemoglobin.

Accepted Answer

Carbon monoxide, when inhaled, combines with haemoglobin of blood to form carboxyhaemoglobin which inhibits the transport of oxygen.

Question 8

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : Glass tumbler breaks in winter when hot water is poured in it. Reason (R) : When hot water is poured. the outer surface of glass expands.

Accepted Answer

When in winter, hot water is poured in the glass tumbler. its inner surface tends to expand while the Outer surface in contact with cold atmosphere does not. This opposite interaction causes the tumbler to break.

Question 9

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : Cotton is grown in alluvial soils. Reason (R) : Alluvial soils are very fertile.

Accepted Answer

Alluvial soils comprising of silt and sand carried down by the rivers, are very fertile. However, cotton is grown in black soil that suits its mineral requirements

Question 10

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion(A) : A little gap is left between iron rails. Reason (R) : Iron expands in summer.

Accepted Answer

Iron expands in summer. So, gaps are left between rails to allow for expansion.

Question 11

Assertion(A) : The pouring of kerosene oil on stagnant pools helps to eradicate malaria. Reason(R) : The kerosene oil is poisonous for the mosquitoes.

Accepted Answer

The kerosene oil sprayed on the water provodes a thin cating and the larvae of the mosquitoes are prevented from coming up to breathe. Thus, they die. Hence, A is true but R is false.

Question 12

Assertion(A) : The steam engine was invented by James Watt. Reason(R) : There was a problem of taking out water from flooded mines.

Accepted Answer

The problem of pumping out water from the flooded mines provided the need of self-working engine, which led James Watt to invent the same. Thus, both A and R are true & R correctly explains A.

Question 13

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion(A) : When common salt is kept open, it absorbs moisture from the air. Reason (R) : Common salt contains magnesium chloride.

Accepted Answer

Magnesium chloride present in common salt is a deliquescent substance i.e. it absorbs moisture from the air when kept in open.

Question 14

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion(A) : Tamil Nadu gets most of the rainfall in winter. Reason (R) : Tamil Nadu gets rainfall from retreating monsoons.

Accepted Answer

Rainfall in Tamil Nadu is caused by the retreating monsoons which occur in winter.

Question 15

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : Razia Sultan was the daughter of Iltutmish. Reason (R) : Iltutmish was a rebel.

Accepted Answer

litutmish was a ruler of slave dynasty and Razia was his daughter.

Question 16

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : The Indian Constitution came into force with effect from 26th January. 1950. Reason (R) : 26th January is celebrated as the Republic Day.

Accepted Answer

The Indian Constitution came into force with effect from January 26, 1950 and since then this day is celebrated as the Republic Day.

Question 17

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : Silver is not used to make electric wires. Reason (R) : Silver is a bad conductor.

Accepted Answer

Silver is a good conductor of electricity but it is not used to make electric wires because it is expensive

Question 18

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : a Vaccines prevent diseases. Reason (R) : Vaccines must be given to children.

Accepted Answer

Vaccines prevent diseases by developing immunity inside the body and vaccines must be given to children to build in them a resistance against diseases.

Question 19

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : Shivaji developed the guerilla warfare. Reason (R) : Shivaji feared the Mughals.

Accepted Answer

Shivaji initiated the guerilla warfare to defeat the Mughuls but he did not fear them.

Question 20

Directions : For the Assertion (A) and Reason (R) below, choose the correct alternative Assertion (A) : Himalayas once laid under the sea. Reason (R) : Fossils of marine creatures are traced on the Himalayas.

Accepted Answer

Himalayas are the young fold mountains that at one time are believed to lie inside the Tethys sea. This is evident from the recovery of fossils of marine creatures on its peaks.

Assertion and Reason Questions