When electrons are lost, a ( ) ion is formed.
When electrons are
gained, a ( )
ion is formed.

When electrons are lost a positive ion is formed. When electrons are gained, a negative ion is formed. I hope this helps

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

no simpler subs form complex ones. synthesise = make