How did our solar system begin to form?

• From a dense cloud of interstellar gas and dust.

• From a massive explosion of a star.

• From a collision of two large planets.

• From a giant ice ball that melted.

What process led to the birth of our Sun?

• A swirling disk of matter cooled down.

• Hydrogen fused into helium.

• Asteroids clumped together.

• Water condensed from gas.

What type of material formed the inner planets like Earth and Mars?

• Mostly ice, liquids, and gases.

• Rocky material.

• Hydrogen and helium.

• Volcanic gases.

What gases made up Earth's very first atmosphere?

• Oxygen and nitrogen.

• Hydrogen sulfide, methane, and carbon dioxide.

• Water vapor and helium.

• Ammonia and sulfur dioxide.

How did Earth's Moon form?

• It was a captured asteroid.

• It formed from debris after a Mars-sized planet collided with Earth.

• It was created from volcanic eruptions on early Earth.

• It spun off from Earth due to rapid rotation.

When did Earth's first primitive oceans form?

• When Earth was still very hot.

• After the first supercontinent appeared.

• When the planet cooled enough for water vapor to condense into liquid.

• After cyanobacteria evolved.

What organisms were Earth's first photosynthesizers and produced oxygen?

• Microscopic organisms.

• Early fish.

• Cyanobacteria.

• Algae.

Which supercontinent is mentioned as possibly being the largest to ever cover the planet?

• Vaalbara.

• Pannotia.

• Pangaea.

• Rodinia.

What characteristic did animals that evolved during the Cambrian Explosion often have?

• Soft, jelly-like bodies

• Hard body parts like shells or spines

• Ability to fly

• Large, feathered wings

When did Earth experience its first mass extinction event?

• Around 250 million years ago

• Around 66 million years ago

• Around 440 million years ago

• Around 10,000 years ago