## Chemistry and Chemical Reactivity (9th Edition)

From the ideal gas law: $m/V=PM/RT$ $M=0.082057\ L.atm/mol.K×(25+273)\ K/(24.8\ mmHg×1\ atm/760\ mmHg)×0.0125\ g/0.125\ L$ $M=74.94\ g/mol$ Atomic weights: B: 10.81 g/mol, H: 1.008 g/mol Closest option: $B_6H_{10}$ $6×10.81+10×1.008=74.94\ g/mol$