If equal volumes of 0.1 M NaOH and 0.1 M H2SO4 are mixed, the resulting solution will contain

• A. H2SO4 and Na2SO4
• B. NaOH and Na2SO4
• C. H2SO4 and NaOH
• D. Na2SO4

Answer: (A)

When a strong base (NaOH) reacts with a diprotic strong acid (H2SO4), the base neutralizes the acid’s protons. Sulfuric acid has two acidic protons, so to make the fully neutralized salt Na2SO4 you’d need two equivalents of base per equivalent of acid. Here, equal volumes with the same concentrations give equal moles of NaOH and H2SO4, i.e., one NaOH per H2SO4 molecule. That means only one proton from each H2SO4 can be neutralized, forming the monosodium sulfate salt: NaHSO4, plus water. The remaining species in solution are Na+ and HSO4− (which come from NaHSO4) rather than free H2SO4 or Na2SO4. So the dominant product is the bisulfate form, NaHSO4, in water.

Among the listed options, the exact species NaHSO4 isn’t shown, but the correct stoichiometric result is that you don’t end up with Na2SO4 or with unneutralized H2SO4 in this 1:1 scenario; you form the monosodium sulfate salt (and water), i.e., NaHSO4 in solution.