Explanation:
Flourine has atomic number of 9 and hence 9 electrons in its neutral state. The full electronic configuration is given as;
1s2 2s2 2p5
Carbon has atomic number of 6 and hence 6 electrons in it's neutral state. The noble gas notation as the following format;
[closest noble gas before the element] remaining electrons
The nearest noble gas to carbon is Helium, the noble gas notation is given as;
[He] 2s4
Mass of solute ( m1 ) = 50.0 g
mass of solvent ( m2 ) = 150.0 g
Therefore:
m/m = ( m1 / m1 + m2 )
m/m = ( 50.0 / 50.0 + 150.0 )
m/m = ( 50.0 / 200 )
m/m = 0.25
Answer : The most likely happens during this reaction is, Oxidation-reduction
Explanation :
The balanced reaction will be,

In this reaction, neutral iron loses 3 electrons and oxidizes in (+3) state,
and neutral oxygen gains 2 electrons and reduces in (-2) state,
When iron react with oxygen gas to give iron oxide. This process is known as iron rusting. During the reaction, oxidation-reduction process occurs.
Oxidation : It is a type of chemical reaction in which a substance loses its electrons. Or we can say that in oxidation, the oxidation number increases.
Reduction : It is a type of chemical reaction in which a substance gains its electrons. Or we can say that in reduction, the oxidation number decreases.