How many moles of oxygen are needed to react with 170 g of hydrazine?

1 answer

You don't furnish an equation. Using the following equation
N2H4 + O2 ==> 2H2O + N2

mols N2H4 = grams/molar mass = 170/32 = approx 5 but you need to redo that.
Since it is 1 mol N2H4 to 1 mol O2, mols N2H4 = mols O2.