Which type of cloud is often associated with thunderstorms and severe weather?

Which gas is commonly used for refrigeration?

What is the primary component of natural gas?

What is the primary function of the cell membrane?

What is the term for the process by which a river wears away the land and carries sediment downstream?

Which type of galaxy has a flattened disk structure with spiral arms and a central bulge?

Which moon of Neptune is the coldest known object in our solar system, with surface temperatures close to absolute zero?

What is the term for the point in a planet's orbit where it is closest to the Sun?

Which gas is responsible for the greenhouse effect on Earth?

Which of the following is a method of relative dating in geology, where rock layers are compared to determine their relative ages?