Question

What is the molality of a solution that contains 63.0 g `HNC_3` in 0.500 kg `H_2O`?

Answer 1

What do you mean by `HNC_3`, do you mean `H_2NCH_3`, i.e. `"methylamine"`?

Explanation:

If you mean `"methylamine"`, then the molality of the solution is given by:

`"Moles of solute"/"Kilograms of solvent"=((63.0*g)/(31.06*g*mol^-1))/(0.500*kg)=4.06*mol*kg^-1`.

I would not want to be downwind of such a solution. It would smell VILE! If you mean a different solute, you must specify the unambiguous chemical formula. The molarity of the solution would not be significantly different.