potassium and oxygen\nexpress your answer as a chemical formula.\na chemical reaction does not occur for…

Explanation:

Step1: Determine potassium ion

Potassium (K) is in Group 1 of the periodic - table and forms a $K^+$ ion with a +1 charge.

Step2: Determine oxygen ion

Oxygen (O) is in Group 16 of the periodic - table and forms an $O^{2 - }$ ion with a - 2 charge.

Step3: Balance charges

To balance the charges, we need 2 potassium ions for every 1 oxygen ion. So the chemical formula is $K_2O$.

Step4: Determine barium ion

Barium (Ba) is in Group 2 of the periodic - table and forms a $Ba^{2+}$ ion with a +2 charge.

Step5: Determine bromine ion

Bromine (Br) is in Group 17 of the periodic - table and forms a $Br^-$ ion with a - 1 charge.

Step6: Balance charges

To balance the charges, we need 2 bromine ions for every 1 barium ion. So the chemical formula is $BaBr_2$.

Answer:

Part A: $K_2O$ Part D: $BaBr_2$