The molality is 0.54 M when 1.34 moles of NaCl is present in 2.47 kg of solvent.
<u>Explanation:</u>
Molality is the measure of how much of amount of solute is dissolved in the solvent. So it is calculated as the ratio of moles of solute to the grams of solvent.

As in this case, the solute is NaCl and solvent is unknown. So the moles of solute is given as 1.34 moles and the mass of solvent is given as 2.47 kg.
Hence, 
Thus, the molality is 0.54 M when 1.34 moles of NaCl is present in 2.47 kg of solvent.
Answer:
7.28 mol
Explanation:
2 NaOH + H₂SO₄ = 2 H₂O + Na₂SO₄ -------------------(1)
mole fraction for the reaction is;
2 : 1 = 2 : 1
Number of moles of H₂SO₄ = 7.28 mol
1 mol of H₂SO₄ shall form 1 mole of Na₂SO₄
therefore,
7.28 mol of H₂SO₄ shall form 7.28 mole of Na₂SO₄