What is the molecular formula of C3H2N with 260.24g/mol

C3 H2 N tells you the lowest possible whole number ratio of atoms in that molecule. That empirical formula must have the same ratio as the actual, molecular formula.

The empirical mass and molecular mass must share the same ratio as the formulas do, so find the mass of C3 H2 N : 3 (12g) + 2 (1g) + 14g=52g

Compare that to the molecular weight of 260g.

MF EF = MW EW so MF EF = 260g 52g = 5 the actual formula is five times heavier than the empirical formula, so take the empirical formula and multiply each subscript by 5.