A.1.1.7-1.8

What percentage of Earth's water is in a liquid state?

• 97.5%

• 98.3%

• 99.1%

• 100%

What is the primary hypothesis for the origin of Earth's water?

• Water was present when Earth was formed.

• Water was delivered by colliding asteroids.

• Water was created by volcanic activity.

• Water was formed from atmospheric gases.

What is the approximate volume of water on Earth in cubic kilometres?

• 1.2 billion

• 1.3 billion

• 1.4 billion

• 1.5 billion

Why is it unlikely that water was present on Earth when the planet was formed?

• The planet was too cold.

• The planet was too hot.

• The planet was too dry.

• The planet was too small.

How often do large asteroids (with a diameter greater than 5 km) currently collide with Earth?

• Once every 5 million years

• Once every 10 million years

• Once every 15 million years

• Once every 20 million years

What state of matter is the majority of Earth's water?

• Solid

• Liquid

• Gas

• Plasma

What evidence suggests a heavier bombardment of asteroids in Earth's early history?

• Geological formations

• Fossil records

• Asteroid samples

• Ancient texts

What was the temperature condition on early Earth that would have caused water to boil and be lost to space?

• Below 0°C

• Around 50°C

• Above 100°C

• Exactly 100°C

What proportion of water was found in a recent sample taken from an asteroid?

• A large proportion

• A moderate proportion

• A small proportion

• No water was found

What is the state of the remaining 1.7% of Earth's water that is not in a liquid state?

• Solid and gas

• Plasma and gas

• Solid and plasma

• Gas and plasma