Final answer:
The correct formulas for the binary ionic compounds are beryllium chloride (BeCl2), cesium sulfide (Cs2S), sodium iodide (NaI), and strontium oxide (SrO), based on the need to balance the charges between the metal cations and non-metal anions. Correct option is a.
Step-by-step explanation:
When writing the formulas for binary ionic compounds, we need to ensure that the total positive charge from the metal cation equals the total negative charge from the non-metal anion. Here are the formulas:
- (a) beryllium chloride: BeCl2
- (b) cesium sulfide: Cs2S
- (c) sodium iodide: NaI
- (d) strontium oxide: SrO
Beryllium (Be) has a +2 charge, and chlorine (Cl) has a -1 charge. Since the charges must balance, two chloride ions are needed for every beryllium ion, so the formula for beryllium chloride is BeCl2. Similarly, cesium (Cs) has a +1 charge, and sulfur (S) has a -2 charge, so two cesium ions are needed for every sulfide ion, resulting in the formula Cs2S.
Sodium (Na) and iodine (I) both have charges of +1 and -1 respectively, forming a one-to-one compound, so the formula for sodium iodide is NaI. Lastly, strontium (Sr) has a +2 charge, and oxygen (O) has a -2 charge, leading to a one-to-one compound, and the formula for strontium oxide is SrO.