Tides are caused by the gravitational pull of the

(1) Earth on the Moon

(2) Earth on the Sun

(3) Sun and Moon on the Earth

(4) Moon on the Earth

Tides in the sea are caused by

(1) effect of Sun

(2) effect of Moon

(3) eombined effect of Moon and Sun

(4) gravitational force of Earth and Sun

Seawater is saltier than rainwater because

(1) rivers wash away salts from the earth and pour them into the sea

(2) sea beds have salt-producing mines

(3) sea animals are salt-producing

(4) the air around the sea is saltish

In the sea, plants are restricted up to the depth of

(1) 20 m

(2) 200 m

(3) 1000 m

(4) 2000 m

El Nino occurs over

(1) Atlantic Ocean

(2) Indian Ocean

(3) Pacific Ocean

(4) Mediterranean Sea

The Sargasso sea is situated in the :

(1) Atlantic Ocean

(2) Pacific Ocean

(3) Indian Ocean

(4) Arctic Ocean

The eastward continuation of the Brazil current is called:

(1) South Atlantic drift

(2) Counter Equatorial drift

(3) West Atlantic drift

(4) North Atlantic drift

The rapidly growing mass of phytoplankton covering the surface water of a lake or pond is known as :

(1) Eutrophication

(2) Water bloom

(3) Water pollution

(4) Water hyacinth

Which one of the following is a warm ocean current ?

(1) Kurile

(2) Canary

(3) Labrador

(4) Gulf Stream

The rhythmic rise and fall of ocean water twice in a day is called

(1) Tide

(2) Ocean current

(3) Wave

(4) Water cycle

Neap tides are

(1)Strong

(2) Weak

(3) Medium

(4) Very strong