How many moles are contained in 2.00 x 10^25 atoms of calcium

Apure solvent has a vapor pressure the vapor pressure of a solution. a. equal to b. lower than c. higher than

Which of these is a physical property

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.