Good, thanks for the help. There is one last question considering this problem:
One of the substances isoelectronic to Y transforms in the presence of water traces into polymer Z. 1.00 g of Z was dissolved in water and the resulting solution was added to the excess of barium acetate solution. The precipitate with the mass of 2.91 g was formed. Determine the formula of Z and draw its structure.
Isoelectronic - it could be a compound where an element from the ring is replaces with another element or group. I thought that the isoelectronic substance contains -OH groups instead of fluorine. The hydrolysis would be:
When barium is added, I got that the mass of the precipitate is 2.88g. Now the difference is slightly bigger, so I suspect if my solution is right. Is it? If yes what would be the formula of the polymer?