Answer:
D. They react readily with oxygen in the air
When a neutral hydrogen atom loses an electron, a positively-charged particle should remain.
The atomic number of Be is 4, and so it has 2 shells. There are valence electrons in the second, which is the outermost, shell of Be. To get the element with one more shell, there would be 3 shells on the new element, and 1 less valence electron, so the new element should have 1 valence electron. Sodium is the element with 3 shells, and one valence electron which fits perfectly into the description.
Animals use oxygen to convert this food into energy they can use, and to maintain a steady supply of carbon atoms that are necessary for building any animal cells. Respiration also returns carbon dioxide back to the atmosphere as a waste product, where plants can reabsorb it in the process of photosynthesis. hope I helped.
