What are groups of particles held tightly together called?

Which of the following is always a reactant in a combustion reaction? oxygen nitrogen hydrogen carbon

__can be defined as which velocity changes

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?