What is the name of the process by which a substance changes directly from a solid to a gas without passing through the liquid phase?

What is the basic structural and functional unit of life?

Which gas is commonly used for refrigeration?

What is the balanced chemical equation for the reaction between hydrogen and oxygen to form water?

What is the largest organ of the human body?

What is the fluid-filled sac found in animal cells that stores water and waste products?

Which layer of the Earth's atmosphere is characterized by the presence of the ionosphere and where auroras occur?

Which of the following is a fossil fuel formed from the remains of ancient marine organisms?

Which element is essential for organic compounds but is not found in inorganic compounds?

Which of the following is a measure of the total amount of dissolved salts in water, often used to determine water salinity?