Hydrogen has one electron in its outermost shell, while fluorine has seven electron in its outermost shell, hence both hydrogen and fluorine needs a single electron to complete its outermost shell.
That's why there is a single bond between hydrogen and fluorine.
Hence both hydrogen and fluorine share one electron with each other, so option "A" is correct.
The circulation system for mammals is very complex
A. Balloons can be filled with air.
C. Air has mass.
The answer you have is right good job 12
