D. As more electrons are added to an element, the number of electron orbitals being filled increases

The reaction creates dihydrogen, hence if it's uncontrolled it could lead to potentially dangerous amounts of gas being released at once.
The answer would be 0.25 g/mL.
I determined the density by dividing the mass by the volume which gives you the density. D = mass/volume.
<span>6 g / 24 mL = 0.25 g/mL
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Somewhat of the same element, have same amount of protons but different number of neutrons. <span />