Worksheet Solutions: The Hydrosphere | Footprints Class 7: Book Solutions, Notes & Worksheets PDF Download

Multiple Choice Questions (MCQs)

Q2: Which process is responsible for converting water in the oceans into water vapor in the atmosphere?
(a) Precipitation
(b) Evaporation
(c) Condensation
(d) Collection
Ans: (b) Evaporation
The water in the oceans becomes water vapor in the atmosphere through the process of evaporation.

Q3: What is the average salinity of sea water expressed in parts per thousand?
(a) 25
(b) 35
(c) 45
(d) 55
Ans: (b) 35
Usually, the average salinity of sea water is 35 parts per thousand.

Q4: Tides are caused due to the gravitational force exerted by which celestial bodies?
(a) Earth and Sun
(b) Earth and Moon
(c) Moon and Sun
(d) Mars and Venus
Ans: (c) Moon and Sun
Tides are caused due to the gravitational force exerted by the Moon, the Sun, and the rotation of the Earth.

Q5: Which factor does not influence the movement of ocean currents?
(a) Differences in temperature and density of ocean water
(b) Prevailing winds
(c) Rotation of the Earth
(d) Shape of Landmasses
Ans: (d) Shape of Landmasses
The shape of landmasses can obstruct the flow of an ocean current, but it does not influence its movement directly.

Short Questions

Q1: Define the hydrosphere and its significance in sustaining life on Earth.
Ans: The hydrosphere comprises all the different types of water bodies along with groundwater. It plays a vital role in sustaining life on Earth by providing water for various purposes such as drinking, irrigation, transport, and supporting diverse marine life. Additionally, it influences weather and climate patterns.

Q2: Explain the process of tidal formation and the factors affecting tidal heights.
Ans: Tides are caused by the gravitational force exerted by the Moon, the Sun, and the rotation of the Earth. The height of tides varies daily due to the relative positions of the Moon and the Sun with respect to the Earth. During full and new moons, spring tides occur with the greatest difference between high and low tides. Neap tides occur during the first and last quarters of the lunar cycle, resulting in minimal difference between high and low tides.

Q3: Describe the types and significance of ocean currents.
Ans: Ocean currents are classified into warm and cold currents based on temperature. Warm currents flow from the Equatorial region towards the Polar region, while cold currents flow in the opposite direction. Ocean currents influence temperature, weather, and marine life distribution. They also play a crucial role in navigation and shipping.

Q4: Discuss the factors influencing the movement of ocean water.
Ans: Factors influencing the movement of ocean water include differences in temperature and density, variation in salinity, prevailing winds, the Coriolis effect, tides, and interactions with other currents. Additionally, the shape of landmasses can affect ocean currents by obstructing flow and causing changes in direction.

Q5: Why is water conservation important, and what are some suggested measures to prevent water pollution?
Ans: Water conservation is crucial to ensure the sustainable availability of water resources for future generations. Measures to prevent water pollution include reducing industrial and agricultural runoff, implementing wastewater treatment systems, promoting responsible disposal of waste, and raising awareness about water conservation practices among the public.

Fill in the Blanks

Q2: The temperature of ocean water varies with latitude, and the warmest oceanic waters are found in _______ latitudes.
Ans: Tropical

Q3: Ocean currents are caused by several factors, including differences in temperature and _______ of ocean water.
Ans: Density

Q4: Tides clear mud and silt deposits from the mouth of rivers and keep them open for _______.
Ans: Ships

Q5: Tidal energy can be generated from ocean water, while hydroelectricity is generated from _______.
Ans: Rivers

Match the Column

Ans:

• Salinity - The degree of concentration of salt in sea water
• Evaporation - Process of converting water in oceans into vapor
• Tides - Rhythmic rise and fall in the level of sea water
• Ocean Currents - Continuous movement or drift of ocean water
• Tsunami - Series of waves caused by displacement of water

True False

Q2: Ocean currents flow in the opposite direction of prevailing winds in the southern hemisphere.
Ans: True
Due to the Coriolis force, oceanic currents generally move in a clockwise direction in the northern hemisphere and in an anti-clockwise direction in the southern hemisphere.

Q3: The Moon exerts a greater gravitational force on water bodies closer to it, causing tides.
Ans: True
The gravitational force of the Moon causes tides by pulling on the water bodies closer to it.

Q4: Tidal energy cannot be generated from ocean water.
Ans: False
 Tidal energy can be generated from ocean water.

Q5: The temperature of ocean water increases with depth.
Ans: FalseThe temperature of ocean water decreases with depth, as the Sun's rays warm the surface waters more than the deeper waters.