Answer
See the answer below.
Work Step by Step
Number of moles of the gas:
$n=PV/RT$
$n=(17.2/760×1\ atm)×1.85\ L/0.082/294\ K$
$n=1.74×10^{-3}\ mol$
Molecular weight:
$0.150\ g\div 1.74×10^{-3}\ mol=86.4\ g/mol$
The most likely possibility is $ClO_2F$
