1. Determine the mass of nitrogen in one mole of the substance:

* Since 23.4% of the substance is nitrogen, one mole of the substance contains 0.234 moles of nitrogen.

* The molar mass of nitrogen (N) is 14.01 g/mol.

* Therefore, the mass of nitrogen in one mole of the substance is 0.234 mol * 14.01 g/mol = 3.28 g.

2. Determine the total number of moles of nitrogen in one mole of the substance:

* One molecule contains 5 nitrogen atoms.

* Since one mole contains Avogadro's number of molecules (6.022 x 10^23), one mole of the substance contains 5 * 6.022 x 10^23 = 3.011 x 10^24 nitrogen atoms.

3. Calculate the molar mass of the substance:

* The mass of nitrogen per mole of the substance is 3.28 g (from step 1).

* The number of moles of nitrogen per mole of the substance is 3.011 x 10^24 (from step 2).

* Therefore, the molar mass of the substance is (3.28 g) / (3.011 x 10^24) = 1.09 x 10^-24 g/mol.

Important Note: This answer is incredibly small. It's highly likely there's an error in the problem statement. It's very unusual for a substance to have such a low molar mass.