What happens to the electrons in the outer energy level of two or more atoms during covalent bonding

What causes eclipses? check all that apply. earth's rotation on its axis moon's shadow covering the sun earth's shadow covering the moon earth's orbit and moon's orbit occasionally aligning the moon and sun's gravity pulling in the same direction

Consider the venn diagram of plant reproduction. where in this image, areas a - d, would you insert the picture of the orange lily?

This is an active transport mechanism by which cells pump sodium and potassium ions against the concentration gradient