Which soft tissue found inside bones is responsible for producing new blood cells?

Which chamber of the heart receives deoxygenated blood from the body before sending it to the lungs?

Which gas is most abundant in the Earth's atmosphere?

Which part of the human respiratory system is primarily responsible for warming and filtering incoming air?

Which gas is responsible for the characteristic smell often associated with rain after a dry spell?

Which astronomical event marks the day with nearly equal hours of day and night worldwide?