The molecular formula gives the actual number of each kind of atom present in one molecule of the compound. It is a simple multiple of the empirical formula i.e molecular formula.

=(empirical formular)n, where n is a simple whole number. The n can be obtained as follows.

N= Relative molecular formula of a compound/relative molecular mass from empirical formula

The most accurate relative molecular masses are obtained from the mass spectrometer. Therefore the correct relative molecular  formula is that which gives the correct relative molecular mass determined from the mas spectrometer.

The molar volume is the volume occupied by one mole of any gas inder standard conditions. This volume is numerically equal to 22,400cm³ at standard temperature and pressure s.t.p

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