The formula for mercurous nitrate is Hg₂(NO₃)₂, not Hg2NO3 2. Here's how to calculate its molar mass:

* Hg (Mercury): 200.59 g/mol * 2 = 401.18 g/mol

* N (Nitrogen): 14.01 g/mol * 2 = 28.02 g/mol

* O (Oxygen): 16.00 g/mol * 6 = 96.00 g/mol

Total Molar Mass = 401.18 g/mol + 28.02 g/mol + 96.00 g/mol = 525.20 g/mol

Therefore, the molar mass of mercurous nitrate, Hg₂(NO₃)₂, is 525.20 g/mol.