1. Which one of the following layers of the atmosphere is responsible for the deflection of radio waves?

(a) Troposphere

(b) Stratosphere

(c) Mesosphere

(d) Ionosphere

(d) Ionosphere is the top layer of the atmosphere. Radio waves are deflected in the ionosphere of the atmosphere. Ionosphere is composed of D, E and F layers. D layer (60 km from earth) is good at absorbing AM radio waves.

2. Given below are two statements one labelled as Assertion (A) and the other labelled as Reason (R).

Assertion (A) : Areas near the equator receive rainfall throughout the year.

Reason (R) : High temperatures and high humidity cause convectional rain in most afternoons near the equator.

In the context of the above two statements, which one of the following is correct?

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

(b) Both A and R true but R is not a correct explanation of A

(c) A is true but R is false

(d) A is false but R is true

(a) The assertion is correct and reason correctly explains the assertion because due to high temperature the atmospheric air gets heated and rises up. It cools down and precipitates while the cool air descends down to take the place of the vaccum.

3. Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R) :

Assertion (A) : Mangroves are very specialised forest eco-systems of tropical and sub-tropical regions bordering certain sea coasts.

Reason (R) : They stabilise the shoreline and act as bulwark against encroachments by the sea.

In the context of the above two statements, which one of the following is correct?

(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 a correct explanation of A

(c) A is true but R is false

(d) A is false but R is true

(a) Both the statement are correct and reason is correctly explained. Mangroves are found in the bordering region of tropical and sub-tropical sea coast. Mangroves stabilise the shoreline and act as bulwark against sea erosion which make it a specialised forest ecosystem.

4. Diamond ring is a phenomenon observed:

(a) at the start of a total solar eclipse

(b) at the end of a total solar eclipse

(c) only along the peripheral regions of the totality trail

(d) only in the central regions of the totality trail

(c) Diamond ring is observed during solar eclipse, only along the peripheral regions of the totality trail.

5. Which one of the following factors is responsible for the change in the regular direction of the ocean

currents in the Indian Ocean?

(a) Indian Ocean is half an ocean

(b) Indian Ocean has monsoon drift

(c) Indian Ocean is a land-locked ocean

(d) Indian Ocean has greater variation in salinity

(b) Due to the monsoon drift of Indian ocean, its regular direction of the ocean currents changes twice an year.