16.24 Although sulfur catenates, it does not have the extensive chemistry that is found for carbon. Explain briefly.

Lead is more often found in nature as its sulfide than its oxide. Provide a brief rationale for this fact.

If 4.381 g of sodium dihydrogenphosphate and 5.207 g of disodium hydrogenphosphate are dissolved in distilled water and diluted to 100.0 mL, and the pKa for the second ionization of phosphoric acid is 6.85, what is the expected pH of the resulting solution? You answer should have two decimal places and three significant figures.

Please provide at least two methods for hydrogen production, brieflydescribe them, and write the chemical reaction involved.