Science test I need help for answers answer both

Which statement is best described as a atom

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?

‘which reaction would most likely require the use of an inert electrode?