Complete the three words. The oxidation state tells you how many electrons an atom has g , l , or s , in forming a compound.

Gained, Lost , Shared

Explanation:

The oxidation state tells you how many electrons an atom has GAINED , LOST , or SHARED , in forming a compound.

Oxidation state is defined as the  the total number of electrons that an atom gains or loses when forming a chemical bond with another atom.

To form an ionic bond for example in NaCl, Na, with 11 electrons and one valence electron in its outermost shell donates or lose that valence electron to Chlorine  with 17 electron and 7 in its outermost shell. Therefore Sodium, Na acquires the +1 oxidaton state to become stable and Chlorine acquires the -1 oxidation state  to become stable  forming the  NaCl compound.

To form a covalent compound, There must be sharing of electrons between atoms.For example, in PCl3,  The  phosphorous atom with atomic number 15 shares its three unpaired electrons with the single valence electrons of three chlorine atoms. making the four molecules to attain stability with  Phosphorous having +3 and the chlorine atoms having -1 oxidation states

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

nuclear fission produces elements that are heavier than helium.

the elements that are used in nuclear fission and their products are much heavier than helium.