It means that it allows some things to pass through it but now all. (Liquids and gases)
The given word equation is:
Nitrogen trifluoride-->Nitrogen + Fluorine
The chemical formula of nitrogen trifluoride is 
and that of nitrogen gas is 
and fluorine gas is 
.
The balanced chemical equation representing the decomposition reaction of nitrogen trifluoride to nitrogen and fluorine will be,
The chemical formula of fluorine gas will be as fluorine exists as a diatomic gas in it's pure state. The coefficient of fluorine will be 3
Therefore, the correct answer is a) 3F2
Because its structure is drawn by dots which can't describ its structure.
The answer to your question is position and number of chemical shifts give information about the structure of a organic molecule. Chemical shift describes the relative positions of the resonances in an NMR spectrum. It is also the position on the δ scale (ppm - parts per million) where the peak occurs.
