Question

calculate the maximum volume of ammonia gas at stp which could be obtained by boiling 8dm(cube)of 0.651g solution of ammonia (molar volume of gas at stp=22.4dm).

Answer 1

I assume you have a solution containing 0.651 g NH3 in that 8 dm^3. So you can get 0.651 g NH3 if you get all of it and that will occupy, @ STP, 22.4 L/mol. How many moes do you have? That's 0.651/17 = about 0.0382 moles NH3 so the volume will be 0.382 x 22.4 dm^3/mol. By the way, the molar volume is 22.4 moles/dm^3