Q 01/05

Roughly what share of global evaporation comes from the ocean?

A) 46%

B) 66%

C) 86%

D) 96%

Answer · why

C) 86%

The ocean also holds 97% of the planet's water and receives 78% of global precipitation.

Q 02/05

What powers the water cycle?

A) Solar radiation

B) Earth’s rotation

C) Ocean tides

D) Volcanic heat

Answer · why

A) Solar radiation

Solar energy heats water in oceans, lakes and rivers until it evaporates; heat transfers between phases keep the cycle turning.

Q 03/05

After evaporating, about how long does water typically stay in the atmosphere?

A) 9 hours

B) 9 days

C) 9 weeks

D) 9 months

Answer · why

B) 9 days

That short residence time contrasts with groundwater, which can sit underground for more than 10,000 years.

Q 04/05

Groundwater can remain beneath the surface for more than how long before leaving?

A) 10 years

B) 100 years

C) 1,000 years

D) 10,000 years

Answer · why

D) 10,000 years

Aquifers refill slowly, which is why 'fossil' groundwater in arid regions is not treated as a renewable supply.

Q 05/05

About how much water falls as precipitation worldwide each year?

A) 505,000 km³

B) 50,500 km³

C) 5,050,000 km³

D) 5,050 km³

Answer · why

A) 505,000 km³

Nearly 398,000 km³ of that lands on the oceans; the same volume, 505,000 km³, returns to the air as evapotranspiration.