What is the number of kilograms of solvent in a 0.70 molal solution containing 5.0 grams of solute?

Molar mass of solute is 30 g/mol

molality is defined as the number of moles of solute in 1 kg of solvent

number of moles of solute - 5.0 g / 30 g/mol = 0.17 mol

molality of solution is 0.70 mol/kg

the mass of solvent when there are 0.7 mol of solute - 1 kg

then the mass of solvent when there's 0.17 mol of solute - 0.17 mol / 0.7 mol/kg

= 0.242 kg

therefore mass of solvent is 0.242 kg