Question

16 multiple answer 1 point which of these elements are required by life forms on earth? (select all that apply) helium carbon hydrogen oxygen

Explanation:

Carbon is a key - element in organic compounds. Hydrogen is present in water and many biological molecules. Oxygen is essential for cellular respiration. Helium is an inert gas and not a key element for life forms on Earth.

Answer:

• B. Carbon
• C. Hydrogen
• D. Oxygen