Final answer:
The formulas for the ionic compounds Sodium Sulphide and Manganese dioxide are Na2S and MnO2, respectively. Sodium Sulphide consists of two sodium ions and one sulfide ion, while Manganese dioxide consists of one manganese ion paired with two oxygen ions.
Step-by-step explanation:
The student has asked for the formulas of two ionic compounds: (i) Sodium Sulphide and (ii) Manganese dioxide.
The formula for Sodium Sulphide is Na2S. In this ionic compound, sodium (Na) has a +1 charge, and since sulfide (S) has a -2 charge, two sodium ions are needed to balance one sulfide ion resulting in the formula Na2S.
The formula for Manganese dioxide is MnO2. Manganese dioxide is a compound where manganese (Mn) has a +4 oxidation state and oxygen (O) has a -2 charge. Since two oxygen ions are needed to balance the +4 charge of one manganese ion, the formula is MnO2.