Use Dot and cross method to show the bonding of the atoms and state the number of atoms of each element present a. Magnesium and Fluorine
b. Sodium and Fluorine
c. Sodium and Oxygen
d. Aluminum and Iodine

Check the attached one..I only draw the Dot method of Magnesium and Fluorine.. since i love chemistry ..Hope this helps you...Balance you have to do it yourself..If you didn't get the answer let me know in the comments..But you have try okay..

answer; ///i do believe that the correct answer is (b); ///particle composed of two or more atoms bonded together;

- decrease the number of plants and animals living in the water.