All other elements react with other elements to form compounds. In the special case where the reaction produces fixed numbers of the same types of atoms in exactly the same configuration, we say the elements have formed a molecule.
Formula for diarsenic pentoxide
As2O5
The answer which would have been a major difference in the ocean basins is the following one:
<span>B. Mid-ocean ridges would have been chains of mountains.
Given that the waters were lower in the past, those ridges would no longer be just mid-ocean ridges, but complete mountains due to the low levels of water around them.</span>
All alkail metals react with halogens vigorously to produce salt. The alkali metal would loose an electron to form and ion with the halogen