C.
This is basically the definition of percent composition which is how much mass a element contributes to a specific molecule.
If the energy level of a certain element is filled based on the maximum number of allowable electrons per level, then it is no longer reactive. With this, half-filled energy level means that the element may retain those electrons and attract electrons from other elements or it may give off its electrons.
The chemical reaction is expressed as:
2H2 + O2 = 2H2O
To determine the amount of oxygen used in the reaction, we use the amount of water produced and the relation of the substances in the reaction we do as follows:
209 g H2O ( 1 mol / 18.02 g ) ( 1 mol O2 / 2 mol H2O ) ( 32 g / 1 mol ) = 185.57 g O2
An Ionic bond is when you have a metal and a nonmetal element bonded together. In this kind of bonds, the metal atom takes electrons from the nonmetal. on other words, this bond involves the gaining and losing of electrons. The atom that receives the electrons becomes an anion (negatively charged ion) and the one that loses them becomes the cation (positively charged ion)
A covalent bond is a bond created between two nonmetals element. In here, both atoms share the electrons.
Both bonds involve interaction between atoms.