Hydrosphere

All of the above

Reason — The hydrosphere includes all the water present on Earth.

All of the above.

Reason — Apart from the ice stored in the cryosphere, freshwater is available as surface water in rivers, lakes, and streams; as groundwater stored beneath the Earth's surface; and as water stored in man-made reservoirs and dams. Therefore, all the options listed are sources of freshwater.

All of the above

Reason — Rainwater that seeps into the ground is stored as groundwater in the soil, subsoil, and underground water-bearing layers (aquifers). Hence, the correct answer is All of the above.

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

Explanation — Waves are oscillatory movements characterized by the alternate rise and fall of the sea surface. They are mainly generated by the action of wind blowing over the surface of the sea. Therefore, the reason correctly explains why waves are formed.

Tides

Reason — Tides are the periodic rise and fall of sea water caused by the gravitational pull of the Moon and the Sun. In contrast, waves are oscillatory movements of sea water mainly caused by winds blowing over the ocean surface.

Tidal range

Reason — The tidal range is the difference in the height of sea level between high tide and low tide.

maximum, minimum

Reason — The Moon revolves around the Earth in an elliptical orbit, so its distance from the Earth varies. The apogee is the point where the Moon is farthest from the Earth (maximum distance), while the perigee is the point where it is closest to the Earth (minimum distance).

A: High tide B: Low tide

Reason — The side of the Earth facing the Moon (A) experiences the greatest gravitational pull, causing a high tide. At right angles to it (B), the water level falls, resulting in a low tide.

A is true but R is false.

Explanation — The tidal range (the difference between high tide and low tide) is not constant. It mainly varies due to the changing positions of the Moon and the Sun and the Moon's varying distance from the Earth (perigee and apogee). The Earth's rotation causes the regular occurrence of tides but does not cause variations in the tidal range.

(A) (B) (C)

Reason — A tide is the alternate advance and retreat of sea water along a coast. When the sea water advances to its greatest extent onto the shore, it is called high tide; when it recedes to its greatest extent, it is called low tide. Statement (D) is incorrect because tides are a characteristic feature of oceans and seas.

Warm currents

Reason — Warm currents flow from the low latitudes (tropical regions) towards the high latitudes (temperate and polar regions), carrying warm water into colder areas. In contrast, cold currents flow from the high latitudes towards the low latitudes, carrying cold water into warmer regions.

The Earth's Revolution

Reason — Ocean currents are influenced by factors such as temperature, salinity, planetary winds, the Earth's rotation, and the shape of continents (landmasses). The Earth's rotation causes the Coriolis effect, which deflects ocean currents. However, the Earth's revolution around the Sun is not a direct cause of ocean currents.

The latter is more saline.

Reason — The Mediterranean Sea has higher salinity than the Atlantic Ocean. As a result, its water is denser, while the less saline and lighter Atlantic water flows over the surface into the Mediterranean Sea through the Strait of Gibraltar. The denser Mediterranean water flows out beneath the Atlantic water.

Trade Winds

Reason — Trade Winds are permanent planetary winds that blow from the subtropical high-pressure belts (around 30° N and 30° S) towards the Equatorial low-pressure belt. They prevail between the Equator and the Tropics. These winds also help drive warm ocean currents westward in the tropical regions.

Anticyclonic

Reason — The pattern of ocean circulation broadly corresponds to the Earth's atmospheric circulation. In the middle latitudes, air circulation over the oceans is predominantly anticyclonic, especially in the Southern Hemisphere, while cyclonic circulation is more common at higher latitudes.

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

Explanation — The Gulf Stream is part of the North Atlantic Ocean gyre, which circulates in a clockwise direction in the Northern Hemisphere. This is mainly due to the Coriolis effect caused by the Earth's rotation, together with the influence of planetary winds and the shape of the continents. Therefore, the reason correctly explains the assertion.

The North Atlantic Drift

Reason — The warm Gulf Stream is deflected eastwards by the Westerlies and the rotation of the earth and reaches Europe as the North Atlantic Drift. It is a warm current which keeps the ports of Great Britain and the rest of western Europe free from ice even in winter, and the British Isles enjoy a mild climate on account of its influence.

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

Explanation — The Labrador Current remains frozen for nine months on account of the influence of the cold Arctic Current.

Gulf Stream — North Atlantic Drift

Reason — The Gulf Stream and its extension, the North Atlantic Drift, are warm currents of the Atlantic Ocean. The Labrador, Irminger, and Canary Currents are cold currents. The Alaska and California Currents are found in the Pacific Ocean, not the Atlantic.

North Atlantic Drift

Reason — The Gulf Stream, a warm ocean current, is deflected eastward by the Westerlies and the Coriolis effect (caused by the Earth's rotation). It then continues across the North Atlantic as the North Atlantic Drift, warming the coasts of Western Europe.

Both A and R are true but R does not explain A.

Explanation — While both statements are scientifically accurate, the Reason describes surface runoff, which is the opposite of how underground water is formed. For R to be the correct explanation of A, it would need to explain infiltration that is, how water seeps down into the ground rather than how it flows on top of it.

A is false but R is true.

Explanation — On the seventh or eighth day of every fortnight a neap tide, which is lower in height than a normal tide, occurs. The height of neap tides is generally 20 per cent lower than that of the normal tides.

Kuroshio current

Reason — The Kuroshio Current is a warm ocean current in the western North Pacific Ocean. It is also known as the Black Stream, as Kuroshio is the Japanese term meaning "Black Current" or "Black Stream", referring to the deep blue-black appearance of its waters. It is also called the Japan Current.

Gulf Stream

Reason — The Gulf Stream is a warm ocean current that raises the temperature of nearby coastal regions and helps keep many ports ice-free during winter. Owing to its influence, the Port of Montreal on the St. Lawrence River remains open for navigation for most of the year, unlike ports affected by cold currents, such as Vladivostok, which remain ice-bound in winter.

Both (1) and (3)

Reason — The Labrador Current meets the warm Gulf Stream near the Grand Banks of Newfoundland, creating one of the world's richest fishing grounds. Similarly, the cold Oyashio Current meets the warm Kuroshio Current off the coast of Japan, forming another rich fishing ground. Therefore, both (1) and (3) are correct.

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

Explanation — Warm currents are those currents which flow from the low latitudes in Tropical Zones towards the high latitudes in the Temperate and Sub-polar Zones. They bring warm water into cold water areas, influencing climate and marine life.

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

Explanation — The pattern of ocean circulation broadly corresponds to the Earth's atmospheric circulation because ocean currents are largely driven by the prevailing winds and influenced by the Coriolis effect. Since air circulation over the oceans in the middle latitudes is mainly anticyclonic, the ocean circulation in these latitudes also follows an anticyclonic pattern.

all of the above

Reason — Ocean currents influence the temperature of coastal regions, making them warmer or cooler. Warm currents generally increase rainfall, while cold currents reduce it. Ocean currents also bring nutrient-rich waters that promote the growth of plankton, supporting abundant fish populations. Hence, ocean currents influence all of the above.

Two ways in which movement of ocean water takes place are-

1. Waves
2. Currents

The rise and fall of sea water due to gravitational forces of the sun and the moon are called tides.

Tides are caused by the gravitational forces of the sun and moon.

The Earth takes 24 hours 52 minutes to complete one rotation relative to the Moon (a lunar day). Since there are two high tides in one lunar day, the interval between successive high tides is about 12 hours 26 minutes. This time interval is due to the Earth's rotation and the Moon's revolution around the Earth.

Spring tides are very high tides that occur when the Sun, the Moon, and the Earth are almost in the same line. At this time, the gravitational pull of the Sun and the Moon combine to produce very high tides.

Neap tides occur on the seventh or eighth day of each fortnight, when the Sun, the Earth, and the Moon are in quadrature (at right angles). The tide-producing forces of the Sun and the Moon act at right angles to each other, resulting in tides that are lower than normal.

The phenomenon that Mona observed is called a Low Tide.

Tides are the periodic rise and fall of sea level caused by the gravitational pull of the Moon and the Sun. During low tide, the sea water recedes from the shore, lowering the water level. As a result, boats at the jetty appear to have sunk, and the gangways become steep or almost vertical.

Two types of ocean currents based on their temperature are-

1. The Warm Currents, e.g. Gulf Stream
2. The Cold Currents, e.g. Labrador current

The Gulf Stream is a powerful warm ocean current affecting the climate of east coast of North America and west coast of Europe. It is also a potential source of renewable power generation.

The combination of warm and cold currents produces heavy fogs and creates rich fishing grounds.

Tara explained that the heavy fog along the coast of Newfoundland is caused by the meeting of the warm Gulf Stream and the cold Labrador Current. The warm, moisture-laden air over the Gulf Stream cools rapidly on coming into contact with the cold Labrador Current, causing the water vapour to condense into thick fog.

The meeting of these two currents also creates one of the world's richest fishing grounds. Therefore, the main occupation of the people of Newfoundland is fishing.

Tides are formed due to the gravitational pull of the Moon and the Sun on the Earth's oceans. The Moon's gravitational pull has the greater effect. As the Earth rotates, the sea water rises and falls, producing high tides and low tides.

When the Sun, the Earth, and the Moon are in a straight line, their gravitational forces combine to produce spring tides, which have the greatest tidal range. When the Sun and the Moon are at right angles with respect to the Earth, their gravitational forces partly oppose each other, producing neap tides, which have a smaller tidal range.

(i) Because the Earth rotates through two tidal bulges every lunar day, coastal areas experience two high and two low tides every 24 hours and 52 minutes. This occurs because the moon is revolving around the Earth in the same direction as the Earth is rotating on its axis.

(ii) Each day a tide is delayed by 26 minutes because the moon also rotates on its axis while revolving around the earth. Since the earth rotates from west to east the tide centre shifts westwards. When the tide centre completes one round, the moon's position is ahead of the tide centre by that time. This delays the tide by 26 minutes each day.

(iii) The tidal range differs from one water body to the other as tidal range is not constant but changes depending on the locations of the moon and the sun.

Below diagram shows the formation of spring and neap tides:

The two types of ocean currents based on their temperature are-

1. The Warm Current — These are those currents which flow from the low latitudes in Tropical Zones towards the high latitudes in the Temperate and Sub-polar Zones. They bring warm water into cold water areas. For example, Gulf Stream.

2. The Cold Current — These currents have a lower surface temperature and bring cold water into warm water areas. These currents flow from the high latitudes in the Polar regions towards the low latitudes in the warm Equator region. For example, Labrador current.

Two factors responsible for causing the currents are-

1. Level of Salinity
2. Temperature

(i) Warm currents produce a milder climate because warm currents tend to raise the temperature of the places where they flow.

(ii) The eastern coast of USA is comparatively cold because of the cold Labrador Current.

(iii) The coasts of Norway are not frozen in winter whereas its adjoining coasts are frozen for most parts of the year on account of the influence of the warm North Atlantic Drift.

(i) The waters of the Labrador current have a cooling effect on the Canadian Atlantic provinces and coastal New England.

(ii) The warm waters of the Kuroshio current sustain the coral reefs of Japan, which are the northernmost coral reefs in the world.

(iii) Oyashio current has an important impact on the climate of the Russian Far East, mainly in Kamchatka and Chukotka.

The Gulf Stream originates in the Gulf of Mexico, flows through the Strait of Florida along the eastern coast of North America, and then crosses the Atlantic Ocean. Near 30°W, 40°N, it divides, with one branch becoming the North Atlantic Drift towards Europe and the other turning south towards West Africa.

The Gulf Stream influences the climate of the east coast of North America from Florida to Newfoundland, and the west coast of Europe. The current keeps these regions warm in winter.

(i) The waters of the Oyashio Current form the richest fishing grounds in the world owing to the extremely high nutrient content of the cold water and the very high tides in some areas, which further enhances the availability of nutrients.

(ii) Warm currents flow towards Queensland which make the air warm and enable it to acquire greater moisture. Thus, the winds increase the amount of precipitation in Queensland while Atacama desert owe their existence to some extent to Benguela and Peru currents which are cold and keep the air dry and devoid of moisture.

(iii) Rich fishing grounds are located on the Pacific coast of North America due to the convergence of warm and cold currents.

Three major effects of currents are-

1. Effect on Climate — The climate of the coasts becomes warm or cool according to the current washing the coast which may be warm or cool.

2. Effect on Marine life — Ocean currents move organic material off the coast which is the food of planktons. The more the planktons, higher the concentration of fish.

3. Effect on commerce — On account of influence of warm currents, harbours are kept open in winter, facilitating trade throughout the year.

The wave observed was a high tide (spring tide), as it was a New Moon Day. High tide occurs when sea water rises and moves towards the coast due to the gravitational pull of the Moon and the Sun. During the new moon, the Sun, the Moon, and the Earth are nearly in a straight line, producing spring tides, which have the greatest tidal range.

The next high tide will occur after approximately 12 hours and 26 minutes.

The consequences of ocean currents ceasing would have significant effects on human beings:

1. Extreme Climate Changes — Heat would not be distributed from the Equator to the poles, leading to extreme temperatures.
2. Changes in Rainfall — Coastal regions would experience changes in rainfall, causing droughts in some areas and floods in others.
3. Decline in Fisheries — The supply of nutrients to the oceans would decrease, reducing plankton growth and fish populations.
4. Disruption of Navigation and Trade — Ocean routes used by ships would be affected, increasing travel time and costs.
5. Adverse Effects on Coastal Economies — Fishing, tourism, and other coastal industries would suffer.

Thus, the absence of ocean currents would seriously affect climate, marine life, and human activities.