Zirconium has an atomic number of 40 and an atomic mass of 91. how many neutrons does it have?

Based on the data in your tables, did the light-colored moths have a higher or lower survival rate after the industrial revolution?

What's the waste product of electrons and pyruvate combining in fermentation?  

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