Why is a crystal lattice the most stable structural form for an ionic compound?

Is this a single replacement reaction or there is no

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 statement describes the phase change that occurs when dry ice is placed in an open container at room temperature?