Why does the boiling point of water change at high elevation (maybe in Denver, Colorado, the Mile-High City) compared to sea level (maybe in Ocean County, New Jersey)?

Explanation:

This is due to a reduction in atmospheric pressure – pressure due to the weight of the overlying air column). Remember that the higher the altitude the lower the air density and subsequently the lower the air pressure.

Therefore when heating water at higher altitude the vapor pressure of the water at the surface overpowers the atmospheric pressure – which is slightly lower than at sea level – even before the water temperatures reach 100 degrees centigrade.

where's the diagram?

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms