Look at the diagram. What number needs to be added to balance the equation?

2

Explanation:

because hydrogen is a diatomic element, so it can't be just H

the answer is 303.15 or 303

under a microscope, cancer cells may look very different from normal cells. they often have different sizes and some may be larger than normal while others are smaller. cancer cells are often abnormally shaped and the control centre of the cell (the nucleus) may have an abnormal appearance.

i think? ?