
<em>Chemists use the mole unit to represent 6.022 × 10 23 things, whether the things are atoms of elements or molecules of compounds. This number, called Avogadro's number, is important because this number of atoms or molecules has the same mass in grams as one atom or molecule has in atomic mass units. </em>
hope helpful~
That would be true, since most other stats include helium, calcium, etc
D milk turning sour
the other options are physical changes
Chemical energy being changed into light energy would happen during phototsynthesis