First step is to write the balanced equation as follows:
NH4NO3(aq)→N2O(g)+2H2O(l)
where (aq) means aqueous and (l) means liquid
From this equation, we find that 1 mole of NH4NO3 yields 2 moles of H2O, thus the ratio between them is 1/2
Now, to get the number of moles (assume it is given the symbol 'n') of ammonium nitrate to form 0.692 moles of water:
n = 0.692 x (1/2) = 0.346 moles
