Answer: B. Sodium sulfate is a soluble salt of a Group I metal. Both reactants — dilute \(\text{H}_2\text{SO}_4\) and \(\text{NaOH}\)(aq) — are soluble, so the 'excess insoluble base + filter' method does not apply. The correct method is acid–alkali titration followed by evaporation/crystallisation.
Step 1: pipette a known volume of one reactant into a conical flask, then add the other from a burette using an indicator to find the end-point. Step 2: repeat without indicator using the same volumes so the solution contains only \(\text{Na}_2\text{SO}_4\). Step 3: evaporate the salt solution in an evaporating dish to obtain crystals.
Filter papers and a filter funnel (options A and C) are not needed because there is no insoluble residue to filter. A balance (option D) is not used in titration. Only B (burette, pipette, evaporating dish) lists the apparatus this method actually requires.
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