What must happen for an ionic bond to be created between two elements?

The name of the ion, s2-, is: sulfurous ion sulfide ion sulfur ion sulfate ion

Answer asap : ( a. how does mucus prevent the entry of pathogens? b. describe two ways white blood cells protect us from pathogens.

Pls ill give u brainliest which of the following is true about science? 1. political conditions are unable to influence it. 2. economic concerns may prevent it from solving problems.