Boron forms a variety of unusual compounds with hydrogen. Achemist isolated `6.3 mg` of one of the boron hybrides in a glass bulb with a volume of `385 mL" at "25^(@)C` and a bulb pressure of 11 torr. the molecular mass of the boron hybride in g `mol^(-1)` is

Options

A. 3.68
B. 27.6
C. 36.35
D. 56.52

Answer

B

Explanation

Assuming ideal gas law , `pV = nRT = (w)/(M) RT implies M = (w RT)/(pV)` , substituting values , we get `M = (6.3 xx 10^(-3) g xx 0.0821 "atm" mol^(-1) K^(-1) xx 298 K)/(11//760 "atm" xx 385 xx 10^(-3) L) = 27.6 g mol^(-1)`