What is an extremophile? What domain is known for these organisms?

Ineed to find the answer of this question because i dont understand it

Asubstance is a good conductor of electricity which of the following best explains a probable position of the substance in a periodic table

What happens to the concentration of hydronium ions as the ph of a solution increases? a. hydronium ion concentration stays the same b. hydronium ion concentration decreases c. hydronium ion concentration increases