Question

Ammonium nitrate a common fertilizer was used by terrorists in the trgic explosion in oklahoma city in 1995.how many litres of gas at 307oc and 1.00atm are formed by the explosive decomposition of 15kg of ammonium nitrate to nitrogen, oxygen and water vapour
Solution
2NH4NO3=2N2 + O2 + 4H2O

Answer 1

mols NH4NO3 = grams/molar mass = ? This is approx 180 but that's just an estimate. You need a more accurate answer.
Then mols N2 formed = 180 x (2 mols N2/2 mols NH4NO3) = approx 180.

mols O2 formed = 180 x (1 mol O2/2 mols NH4NO3) = approx 180/2 = approx 90

mols H2O (gas) formed = 180 x (4 mols H2O/2 mols NH4NO3) = 180 x 2 = approx 360.

Now add mols N2 gas to mols O2 gas to mols H2O gas to find total mols gas. Then use PV = nRT at the conditions listed to find total volume in liters.