You poured in 30.0 mL of 2.0 M NaOH into a calorimeter containing 30.0 mL of 2.0 M HCl.?

Initial number of moles of NaOH = (2.0 mol/L) × (30.0/1000 L) = 0.06 mol
Initial number of moles of HCl = (2.0 mol/L) × (30.0/1000 L) = 0.06 mol

NaOH + HCl → NaCl + H₂O
Mole ratio NaOH : HCl : H₂O = 1 : 1 : 1
Hence, both NaOH and HCl completely react.

No. of moles of H₂O formed = 0.06 mol

In neutralization of strong acid and base, 57.62 kJ of heat is released when 1 mole of water is formed.
q-solution = (57.62 kJ/mol) × (0.06 mol) = 3.46 kJ