NEED ASAP !! A 4.50 L sample of dry air in a cylinder exerts a pressure of 5.00 atm at a temperature of 25 oC. Without a change in temperature, a piston is moved until the pressure in the cylinder is reduced to 1.00 atm. What is the volume of the gas?

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.