Which of the followiing is not a principle of natural selection?

What are the genotypic and phenotypic ratios

Suppose you mix one mole of sulfuric acid (h2so4) with 1 mole of sodium hydroxide(naoh). why does the ph of the solution remain below 7? ( explain so i can get better understanding! )

Using the periodic table, complete the following. element: hydrogen symbol: h₂ molecular weight: g mass of one mole: g/mol