Why is carbon is considered tetravalent?

How do cells grow and reproduce to maintain homeostasis?

Which of the following is the most likely outcome of global warming

Drag each description to the correct location on the image. not all descriptions will be used. describe the parts of a comet. the frozen part of the comet the atmosphere of gases and dust formed when the nucleus vaporizes tail made of small, solid dust particles tail made of ions that appears to point away from the comet's orbit