Question

1. choose the correct answer.

which statement is true?
burning fossil fuels puts oxygen in the air, which may cause global warming.
burning fossil fuels puts carbon dioxide in the air, which may cause global cooling.
burning fossil fuels puts oxygen in the air, which may cause global cooling.
burning fossil fuels puts carbon dioxide in the air, which may cause global warming.

1. choose the correct answer.

most power plants use ____ to create electricity.
oil
natural gas
coal

Explanation:

For question 5: Burning fossil fuels (like coal, oil, gas) undergoes combustion that releases carbon dioxide ($CO_2$), a greenhouse gas that traps heat in the atmosphere, leading to global warming. The other options incorrectly state oxygen release or global cooling.
For question 6: Coal is the most widely used fuel for electricity generation globally among the given options, as it is abundant and has been a traditional power source for power plants.

Answer:

1. Burning fossil fuels puts carbon dioxide in the air, which may cause global warming.
2. coal