Molality is the ratio between amount of substance of solute in moles and amount of solvent in kg.
Molality (M) = (moles of solute)/(mass of solvent)
Here the solute is NaCl and solvent is water.
23.44% wt means we have 23.44g of NaCl in 100ml of water.
For 1000ml of water we have `23.44xx10 = 234.4` g of NaCl.
Molic weight of NaCl = 58.44g/mol
moles of NaCl `= 234.4/58.44 = 4.01` moles
So we have 4.01 moles of NaCl in 1000ml of water.
Usually 1ml of water has a weight of 1g.
So in the solution we have 1000g = 1kg of water.
Molality = 4.01/1 = 4.01mol/kg
The molality of the NaCl solution is 4.01mol/kg