Important Questions: Water - Class 7 MCQ

During these Moon phases, the solar tide coincides with the lunar tide because the Sun and the Moon are aligned with Earth, and their gravitational forces combine to pull the ocean's water in the same direction. These tides are known as spring tides or king tides.

About 71 percent of the Earth's surface is water-covered, and the oceans hold about 96.5 percent of all Earth's water. Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, in the ground as soil moisture and in aquifers.

Topic in NCERT: DISTRIBUTION OF WATER BODIES

Line in NCERT: "We all know that three-fourth of the earth surface is covered by water."

Ocean currents play a crucial role in redistributing heat around the planet by moving warm water from the equator toward the poles and bringing cold water from the poles back toward the equator. This process helps regulate global climate and weather patterns.

Topic in NCERT: OCEAN CURRENTS

Line in NCERT: "Ocean currents are streams of water flowing constantly on the ocean surface in definite directions."

Warm ocean currents flow away from the equatorial region on the western side of ocean basins. The Gulf Stream in the North Atlantic and the KuroshioCurrent in the North Pacific are examples of warm currents. Of all the warm currents, the Gulf Stream has been studied most extensively.

Topic in NCERT: OCEAN CURRENTS

Line in NCERT: "Generally, the warm ocean currents originate near the equator and move towards the poles."

Ocean currents are primarily horizontal water movements. Ocean currents flow for great distances, and together, create the global conveyor belt which plays a dominant role in determining the climate of many of the Earth's regions.

Topic in NCERT: OCEAN CURRENTS

Line in NCERT: "Ocean currents are streams of water flowing constantly on the ocean surface in definite directions."

The Labrador Current is a cold current in the North Atlantic Ocean which flows from the Arctic Ocean south along the coast of Labrador and passes around Newfoundland, continuing south along the east coast of Nova Scotia. It is a continuation of the West Greenland Current and the Baffin Island Current.

Topic in NCERT: OCEAN CURRENTS

Line in NCERT: "The Labrador Ocean current is cold current while the Gulf Stream is a warm current."

Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of approximately 3.5%, or 35 parts per thousand. This means that for every 1 litre (1000 mL) of seawater there are 35 grams of salts (mostly, but not entirely, sodium chloride) dissolved in it.

Topic in NCERT: SALINITY OF OCEANS

Line in NCERT: "The average salinity of the oceans is 35 parts per thousand."

The water cycle refers to the continuous movement of water through evaporation, condensation, and precipitation, circulating between the oceans, atmosphere, and land​.

The Dead Sea has a salinity of 340 grams per liter of water, making it extremely dense. This increased density allows swimmers to float easily.

Topic in NCERT: DISTRIBUTION OF WATER BODIES

Line in NCERT: "Swimmers can float in it because the increased salt content makes it dense."

Before a tsunami strikes, the water along the coastline often retreats rapidly, exposing areas of the seabed​.