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An observation that requires measurement is called quantitative observable or qualitative

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.

At a certain temperature the rate of this reaction is first order in hi with a rate constant of : 0.0632s2hig=h2g+i2g suppose a vessel contains hi at a concentration of 1.28m . calculate how long it takes for the concentration of hi to decrease to 17.0% of its initial value. you may assume no other reaction is important. round your answer to 2 significant digits.