Question

hiii....how molecular mass equals 2 ×vapour density......derive plss.....'^_^'

Answer 1

Vapour density may be defined as mass of a certain volume of a substance divided by mass of same volume of hydrogen.

vapour density = mass of n molecules of gas / mass of n molecules of hydrogen.

Thus:

vapour density = molar mass of gas / molar mass of H2

vapour density = molar mass of gas / 2.016

vapour density = ~½ × molar mass

(and thus: molar mass = ~2 × vapour density

Answer 2

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Mere dil ki baatein kahungi tujhe,
Shayad tu badi door hai ja chuka,
Main akeli reh gayi na jaane tu kahan kho gaya