There is 1 mole of propane (C3H8) for every 3 moles CO2. How many moles of CO2 would there be if you started with 2 moles of propane instead of 1?

The number  of seconds for  the concentration  to decrease  to  0.13 mol  for a second  order  reaction is  calculated  using  the below  formula

1/At  =-Kt  +1/Ao  where  At   is  the final concentration, Ao  is the   initial concentration.  t = time in second   while k =  constant

1/0.13 =-0.13 (t) + 1/0.26
like terms together

1/0.13-1/0.26 =-0.13 t
divide both side by 0.13

T =29.6 seconds