Which solution is the most concentrated?

2.0 mL of 10 M H2SO4, where H2SO4 has a molar mass of 98 g/mol

5.0 mL of 1.0 M PbSO4, where PbSO4 has a molar mass of 303 g/mol

2.0 mL of 10.5 M H2O2, where H2O2 has a molar mass of 34 g/mol

100 mL of 10 M NaCl, where NaCl has a molar mass of 58 g/mol

To answer this, we find the amount of the substance in the solution in terms of moles. Calculations are as follows:

2.0 mL of 10 M H2SO4, where H2SO4 has a molar mass of 98 g/mol

10 mol / L H2SO4 (0.002 L) = 0.02 mol

5.0 mL of 1.0 M PbSO4, where PbSO4 has a molar mass of 303 g/mol

1.0 mol / L PbSO4 (0.005 L) = 0.005 mol

2.0 mL of 10.5 M H2O2, where H2O2 has a molar mass of 34 g/mol

10.5 mol / L H2O2 (0.002 L) = 0.021 mol

100 mL of 10 M NaCl, where NaCl has a molar mass of 58 g/mol

10 mol / L NaCl (0.1 L) = 1 mol

Therefore, the correct answer is the last option.