Rinman's green is:

Options

A. `[Ni(NH_(3))_(6)]SO_(4)`
B. `FeSO_(4)*7H_(2)O`
C. `CoZnO_(2)`
D. `Fe(BO_(2))_(2)`

Answer

To determine which compound is known as Riemann's Green, we will analyze the provided options step by step.

### Step 1: Identify the Options
The options given are:
1. Ni(NH3)6 SO4
2. Ferrous sulfate dot 7 H2O
3. CoZnO2
4. FeBO2 whole twice

### Step 2: Recall the Definition of Riemann's Green
Riemann's Green is also known as cobalt green. Its chemical formula is CoZnO2, which can also be represented as CoO·ZnO.

### Step 3: Analyze Each Option
- **Option 1: Ni(NH3)6 SO4** - This is a nickel complex and is not related to cobalt green.
- **Option 2: Ferrous sulfate dot 7 H2O** - This is ferrous sulfate with water of crystallization and is not cobalt green.
- **Option 3: CoZnO2** - This matches the chemical formula of Riemann's Green (cobalt green).
- **Option 4: FeBO2 whole twice** - This is not related to cobalt green.

### Step 4: Conclusion
Based on the analysis, the compound that is known as Riemann's Green is **CoZnO2**, which corresponds to **Option 3**.

### Final Answer
Riemann's Green is CoZnO2 (Option 3).

---