Which of the following ions is the most reactive?

Cu2+
Pb2+
Au3+
Fe2+

Aaspirin has a density of 1.40 g/cm^3 what is the volume in cubic centimeters of a tablet weighing 320 mg?

6what is the importance of water on earth? a) it keeps the top layer of the geosphere cool b) it allows life to exist c) it provides ice at the poles d) it creates earth's blue color from space

An observation that requires measurement is called quantitative observable or qualitative