The answer is B. This is because Sodium has 1 valence electron and Fluorine has 7 valence electrons. All elements want 8 valence electrons so they may be stale, like the noble gases are. Hope this helps.
It affects our everday life because of new inventions and easier ways to make/produce different stuff!
Atoms are generally neutral because they have an equal amount of protons and electrons.
Volume percent = Volume of solute
----------------------------------
Volume of the solution
2 Volume of the solute
------- = ------------------------------
100 250
Volume of the solute = 2 x 250
------------
100
= 5 mL.
Hope this helps!