1. estimate the surface area of earth in km2. 2. estimate the percentage of earth's surface covered by water. 3. estimate the depth of earth's oceans in km. 4. estimate the volume of earth's oceans in km3. 5. estimate the number of gallons in earth's oceans.

1. 5.101 x 10⁸ Km².

2. 71 %.

3. 3.769 Km.

4. 1360.6 x 10⁶ Km³ = 1.36 billion Km³.

5. 3.597 x 10²⁰ Gallon of water (359 quintillion gallons of water).

Explanation:

1. The surface area of the earth:

Recently, astronomy and the improvement of instrumentation and methodology to see the earth from the space and identifying the shape of the earth as a flattened sphere.

Then we can calculate the surface area of the earth from the relation (4πr²).

The radius of the earth is estimated to be 6371 Km.

The surface area of the earth = 4 π (6371)² = 5.101 x 10⁸ Km².

2. The percentage of Earth's surface covered by water:

The water percentage is about 71 % and the other 29 % is corresponding to the island and continents. So, the Earth appeared as a blue marble because water reflects the blue color.

3. The depth of the Earth's oceans:

The average depth of the oceans is about 3796 m = 3.769 Km.

It is noticed that the estimation of the oceans depth decreased over years which reflects more precise determination and estimation of the depth of oceans through years.

4. The volume of the Earth's oceans:

We can calculate the volume of the Earth's oceans by multiplying the area of the oceans by its depth (Area x depth).

The area of the oceans is estimated to be 361 x 10⁶ Km², and the depth is determined to be about 3.679 Km.

The volume of Earth's ocean = (361 x 10⁶ Km²) (3.679 Km) = 1360.6 x 10⁶ Km³ = 1.36 billion Km³.

5. The number of gallons in Earth's oceans:

The water occupies the estimated area of the oceans (1360.6 x 10⁶ Km³ = 1.360 x 10¹⁸ m³).

Knowing that (1 Gallon = 0.003785 m³), then the number of gallons of water in Gallons is equal 3.597 x 10²⁰ Gallon of water (359 quintillion gallons of water).