Is our earth covered by 78% water and 22% land ?

getting started.

Strait of Gibraltar Space Shuttle view of the Strait of Gibraltar

71 Percent of the Earth's surface is covered with water. Earth is the only planet on which water can exist in liquid form on the surface (though there may be liquid ethane or methane on Titan's surface and liquid water beneath the surface of Europa). Liquid water is, of course, essential for life as we know it. The heat capacity of the oceans is also very important in keeping the Earth's temperature relatively stable. Liquid water is also responsible for most of the erosion and weathering of the Earth's continents, a process unique in the solar system today (though it may have occurred on Mars in the past).

Earth's atmosphere Earth's atmosphere seen at the limb

The Earth's atmosphere is 77% nitrogen, 21% oxygen, with traces of argon, carbon dioxide and water. There was probably a very much larger amount of carbon dioxide in the Earth's atmosphere when the Earth was first formed, but it has since been almost all incorporated into carbonate rocks and to a lesser extent dissolved into the oceans and consumed by living plants. Plate tectonics and biological processes now maintain a continual flow of carbon dioxide from the atmosphere to these various "sinks" and back again. The tiny amount of carbon dioxide resident in the atmosphere at any time is extremely important to the maintenance of the Earth's surface temperature via the greenhouse effect. The greenhouse effect raises the average surface temperature about 35 degrees C above what it would otherwise be (from a frigid -21 C to a comfortable +14 C); without it the oceans would freeze and life as we know it would be impossible. (Water vapor is also an important greenhouse gas.)

Earth from Apollo 11

Yes. Just because there is undersea water its covered by the ocean. So it would not take into account.

The operative word is "covered". True there is land mass that makes up the sea floor, but it is "covered" by the ocean.

71% covered by water and 29% land.

I think the land covered by the oceans,rivers,lakes is not counted

its 70% water and 30% land

it is 4.64%, because as you said 16% of the 29% of land is suitable for our use, thereofore of the total area of earth, 29*16% = 4.46% is suitable for our use. (I hope I got your question right)

yes...it is...that is the sea bed...if we include the sea bed....there will b no water area into account...

yeas

yes .