Answer:
See below!
Explanation:
For the chemical formula, you need to have enough of each atom so that the charge is zero.
Aluminum has a +3 charge, and fluorine has a -1 charge.  Since the charge has to be zero, you need three fluorines, giving you AlF₃.
Barium has a +2 charge, and oxygen has a -2 charge.  Since the charges are equal in magnitude but opposite in sign, you only need one of each atom giving you BaO.
The name of the ionic compound will be the metal and then the nonmetal.  When putting the nonmetal in, change the ending to "-ide".  For example "chlorine" would be "chloride.
CaCl₂  ==>  calcium chloride
Ga₂S₃  ==>  gallium sulfide
K₃N  ==>  potassium nitride
AlF₃ ==>  aluminum fluoride
BaO  ==>  barium oxide
 
        
             
        
        
        
Answer:
Independent: sizes of nails
Dependent: number of paper clips
Controlled: Battery, wire and type of nails
Explanation:
An independent variable is a variable which when changes does not the effect the results of the experiment. It does not depends upon the dependent variable. 
A dependent variable is defined as a variable which is affected when the independent variable is changed by the researcher or the experimenter. It depends greatly upon the independent variable.
While a controlled variable is that variable whose value is not changed in an experiment. It contains all the constants.
In the context, 
the independent variable are : sizes of nails
the dependent variables are : number of paper clips
the Controlled variables are: Battery, wire and type of nails
 
        
             
        
        
        
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
        
             
        
        
        
Answer: potassium nitrate
hope this helps