How do i fine density given g/mol and ml

molar mass 153.33 g/mol of POCl3
and i have .12ml of POCl3
How do i find density of POCl3?

Not enough information.

Working backwards from the information given:
(1.645 g/mL) x (0.12 mL) = 0.1974 g POCl3

(0.1974 g POCl3) / (153.33 g/mol) = 0.00129 mol POCl3

In order to reach the answer you've shown, you would have to have been given in the question either
0.1974 g POCl3 or 0.00129 mol POCl3 or something equivalent to that.