Ideal Gas Law, Please help me it's due soon

Imagine that twenty i.u.’s of enzyme z were catalyzing the above reaction for one minute, under vmaxconditions, in a 3.00 ml assay volume. the assay is buffered with 20 mm phosphate buffer, ph 7.60. what will the ph be at the end of that one minute?

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.

What is the atomic number of an atom that has 6 protons