Formation of Elements and Reactions

Where are most naturally occurring elements formed?

• In volcanoes

• In stars through nuclear fusion

• In Earth's core

• In comets

What occurs during nuclear fusion in stars?

• Lighter elements combine to form heavier elements

• Atoms split into smaller parts

• Molecules form chemical bonds

• Protons turn into electrons

Which is a correct example of a fusion reaction?

• H → He + energy

• 2H + 2H → He + energy

• C + O → CO

• H₂O → H + O

What marks the beginning of a star's life cycle?

• Supernova

• Nebula

• White dwarf

• Red giant

In which phase of a star's life are elements heavier than iron typically formed?

• Red giant

• Main sequence

• Supernova

• White dwarf

What was the primary component of Earth's early atmosphere?

• Oxygen

• Carbon dioxide

• Nitrogen

• Ozone

What major event led to a significant increase in oxygen in Earth’s atmosphere?

• Volcanic eruptions

• Photosynthesis by early life forms

• Asteroid impacts

• Human activities

Which elements are essential for life on Earth?

• Zinc, Mercury, and Argon

• Helium, Neon, and Fluorine

• Carbon, Hydrogen, Oxygen, and Nitrogen

• Sulfur, Lead, and Uranium

How does the structure of plant leaves relate to their function?

• They are thick to store energy

• They have a large surface area to absorb sunlight

• They are hollow to trap water

• They are hard to protect from herbivores

How are fossil fuels formed?

• From decaying minerals in rocks

• By melting underground lava

• From dead plants and animals compressed over millions of years

• From rainwater reactions underground