Which of the following is the correct chemical formula for cobalt(II) hydroxide?

• A. Co(OH)
• B. Co(OH)2
• C. CoOH
• D. Co2(OH)3

Answer: (B)

Verified step by step guidance

1. Identify the charge of the cobalt ion in cobalt(II) hydroxide. The Roman numeral II indicates that cobalt has a +2 charge, so the ion is Co^{2+}.
2. Recognize the hydroxide ion, OH^{-}, which has a charge of -1.
3. Determine the ratio of cobalt ions to hydroxide ions needed to balance the overall charge to zero. Since cobalt is +2 and hydroxide is -1, two hydroxide ions are needed to balance one cobalt ion.
4. Write the chemical formula by placing the cobalt ion first, followed by the hydroxide ion with a subscript of 2 to indicate two hydroxide ions: Co(OH)_{2}.
5. Confirm that the formula Co(OH)_{2} is electrically neutral, with total positive charge +2 and total negative charge -2, making it the correct formula for cobalt(II) hydroxide.