Background info:
You used 1.05g of solid and it required 17.85mL of 1.00M HCl to titrate to the endpoint.
The number of moles of HCL required in your titration is 0.01780 mol. The mole ratio between the solid and the HCl is 1:1, the molar mass of the solid is 59.70 g/mol. The mole ration between the solid and the HCl is 1:2, the molar mass of the solid is 119.6 g/mol.
Assuming you produced NaOH, what is the percent error in your determined molar mass of NaOH?
Assuming you produced Na2CO3, what is the percent error in your determined molar mass of NaOH?
Assuming you produced Na2O, what is the percent error in your determined molar mass of NaOH?