Question

For question numbers 14, 15 and 16, two statements are given- one labeled Assertion (A) and the

other labeled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c)

and (d) as given below:

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

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

c) A is true, but R is false.

d) A is false, but R is true.

14 Assertion: After white washing the walls, a shiny white finish on walls is

obtained after two to three days.

Reason: Calcium Oxide reacts with Carbon dioxide to form Calcium

Hydrogen Carbonate which gives shiny white finish.

1

15 Assertion: Food chain is responsible for the entry of harmful chemicals in our

bodies.

Reason: The length and complexity of food chains vary greatly.

OR

Assertion: Greater number of individuals are present in lower trophic levels.

Reason: The flow of energy is unidirectional.

1

16 Assertion: A geneticist crossed a pea plant having violet flowers with a pea

plant with white flowers, he got all violet flowers in first generation.

Reason: White colour gene is not passed on to next generation.​

Answer 1

Answer:

14. A is true but R is false

15. A is true but R is false (for both options)

16. A is true but R is false

cool answers!

Answer 2

The questions are answered below:

14 Assertion: After white washing the walls, a shiny white finish on walls is obtained after two to three days.

Reason: Calcium Oxide reacts with Carbon dioxide to form Calcium Hydrogen Carbonate which gives shiny white finish.

c) A is true, but R is false.

• Calcium hydroxide present in the whitewashing material is exposed to the atmosphere after whitewashing.
• This calcium hydroxide reacts with carbon dioxide in the atmosphere to form calcium carbonate.
• This reaction takes around two to three days and calcium carbonate gives the shiny white finish in walls. Thus, the assertion is correct.

• The reason is false as calcium carbonate reacts with carbon dioxide and not calcium oxide.

15 Assertion: Food chain is responsible for the entry of harmful chemicals in our bodies.

Reason: The length and complexity of food chains vary greatly.

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

• There are different trophic levels in a food chain and many organisms are present in each trophic level.
• When toxin enters one trophic level, then because of the food chain, the harmful chemicals enter our body. Thus, the assertion is correct.
• Food chains can start from unicellular organisms and can go up to higher-level organisms.
• Thus, the length and complexity of the food chain vary. Thus reason is correct but it does not explain the assertion.

OR Assertion: Greater number of individuals are present in lower trophic levels.

Reason: The flow of energy is unidirectional.

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

• It is true that many individuals are present in lower trophic levels. Producers are great in number as compared to carnivores.
• The flow of energy is unidirectional as the energy from producers is taken forward from herbivores to carnivores and reverse flow can't take place.
• Thus, both assertion and reason are correct but reason does not explain assertion.

16 Assertion: A geneticist crossed a pea plant having violet flowers with a pea plant with white flowers, he got all violet flowers in first generation.

Reason: White colour gene is not passed on to next generation.​

c) A is true, but R is false.

• Violet trait is the dominant allele in this case. So, if homogenous violet flowers are crossed with white flowers, then all violet flowers will be obtained in the first generation.
• This is because recessive trait needs will not show if a dominant allele is present.
• But, in the next generation, heterozygous violet flowers will be obtained, thus the recessive white colour gene is passed to the next generation.
• Thus, the assertion is correct but the reason is not.