Answer
See the answer below.
Work Step by Step
From the ideal gas law:
$m/V=PM/RT$
$M=0.082057\ L.atm/mol.K×(23+273)\ K/(715\ mmHg×1\ atm/760\ mmHg)×1.007\ g/0.452\ L $
$M=57.52\ g/mol$
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