Hexaamminenickel(II) hexanitrocobaltate(III) can be written as

Options

A. `[Ni(NH_(3))_(6)]_(2) [Co(NO_(2))_(6)]_(3)`
B. `[Ni(NH_(3))_(6)]_(3) [Co(NO_(2))_(6)]_(2)`
C. `[Ni(NH_(3))_(6)][Co(NO_(2))_(6)]`
D. `[Ni(NH_(3))_(6)(NO_(2))_(6)]Co`

Answer

To write the formula for Hexaamminenickel(II) hexanitrocobaltate(III), we will follow these steps:

### Step 1: Identify the components of the coordination compound
- The first part of the name is "Hexaamminenickel(II)", which indicates that we have a nickel ion (Ni) coordinated with six ammonia (NH3) ligands.
- The second part is "hexanitrocobaltate(III)", indicating a cobalt ion (Co) coordinated with six nitro (NO2) ligands and in the +3 oxidation state.

### Step 2: Write the formula for Hexaamminenickel(II)
- The nickel ion has a +2 oxidation state, and each ammonia ligand is neutral. Therefore, the formula for Hexaamminenickel(II) is:
\[ \text{Ni(NH}_3\text{)}_6^{2+} \]

### Step 3: Write the formula for hexanitrocobaltate(III)
- The cobalt ion has a +3 oxidation state, and each nitro ligand has a -1 charge. Therefore, the formula for hexanitrocobaltate(III) is:
\[ \text{Co(NO}_2\text{)}_6^{3-} \]

### Step 4: Combine the two components
- Now, we combine the two parts. The overall charge of the complex must be neutral. The Hexaamminenickel(II) has a charge of +2, and hexanitrocobaltate(III) has a charge of -3. To balance the charges, we need to consider the stoichiometry:
- We need three units of Hexaamminenickel(II) to balance the -3 charge from one unit of hexanitrocobaltate(III).

### Step 5: Write the complete formula
- The complete formula for the coordination compound is:
\[ \text{[Ni(NH}_3\text{)}_6]^{2+} \text{[Co(NO}_2\text{)}_6]^{3-} \]
- To represent the entire compound, we write it as:
\[ \text{Ni(NH}_3\text{)}_6^{3} \text{Co(NO}_2\text{)}_6^{2} \]

### Final Answer
The final formula for Hexaamminenickel(II) hexanitrocobaltate(III) is:
\[ \text{[Ni(NH}_3\text{)}_6]^{3} \text{[Co(NO}_2\text{)}_6]^{2} \]