Answer:
51:49 is the ratio of female participants to male participants.
Explanation:
Percentage of females in the race = 51 %
Percentage of males in the race = 100% - 51 % = 49%
Total participants in race = 400
Number of women participants = 
Number of men participants = 
Ratio of female participants to male participants :
F (Fluorine) is in column (group/family) VIIA, or the "halogens". When you see the halogens (Fluorine, Chlorine, Bromine, and Iodine) in combination with a metal, each halogen atom present will carry a -1 charge. We can see that the atom has no charge, so the metal must cancel out the negative charges brought by the two fluorine atoms.
(Charge on m) + 2*(charge on fluorine) = 0
(Charge on m) + 2*(-1) = 0
(Charge on m) - 2 = 0
Charge on m ion = +2
