Fill in the blanks.

1. An ocean is a large continuous body of water surrounding the ______________.
2. Ocean floors are a storehouse of ______________.
3. The ______________ is 3,650 km long that flows across western Siberia.
4. Lakes are found in all continents except ______________.
5. ______________ constitute about 2% of the total surface fresh water.

Match the following.

State whether true or false.

1. Oceans contain 57 per cent of the Earth's water.
2. Lakes provide long distance communication routes.
3. A sea is smaller and shallower than an ocean.
4. Chilka Lake is the oldest and deepest freshwater lake on Earth.
5. At the end of its journey, a river finally joins a sea or a lake.

Tick the correct answer.

1. Which is the fourth largest ocean on Earth?
   1. Pacific
   2. Atlantic
   3. Arctic
   4. Antarctic
2. Which ocean remains frozen in most parts, almost throughout the year?
   1. Indian
   2. Pacific
   3. Arctic
   4. Antarctic
3. Which sea is a sub-oceanic basin of the western Atlantic Ocean?
   1. Caribbean
   2. Aral
   3. Arabian
   4. Caspian
4. Which is the largest lake in South America?
   1. Baikal
   2. Lake Onega
   3. Lake Titicaca
   4. Chilka Lake
5. Which river is the principal river of northern China that empties into the Bohai Sea?
   1. Nile
   2. Ob
   3. Huang He
   4. Murray

Why is the Pacific Ocean regarded as the deepest ocean in the world? Give geographical reason.