A coordiantion complex compound of cobalt has the molecular formula containing four ammonia molecules, one nitro group and two chlorine atoms. A solution of this complex was prepared by dissolving 2.44 g of it in water and making the volume to 200 mL. Excess of `AgNO_(3)` solution was then added to it and the precipitate of AgCl formed was filtered and dried. The weight of AgCl thus obtained was found to be 1.435 g (Atomic mass of Co=59, Ag=108)
The name of the complex would be

Options

A. tetraamminedichloridocobalt (III) nitrite
B. tetraamminenitrocobalt (III) chloride
C. tetraamminechloridonitrocobalt (III) chloride
D. tetraamminedichloridonitrocobalt (III)

Explanation

To solve the problem, we will follow these steps:

### Step 1: Determine the molecular formula of the coordination complex
The coordination complex contains:
- 4 ammonia (NH₃) molecules
- 1 nitro (NO₂) group
- 2 chloride (Cl) ions

Thus, the molecular formula can be written as:
\[ \text{[Co(NH}_3\text{)}_4\text{Cl}_2\text{NO}_2] \]

### Step 2: Calculate the molar mass of the complex
To find the molar mass, we will sum the atomic masses of all the components:
- Cobalt (Co) = 59 g/mol
- Ammonia (NH₃) = 17 g/mol, and there are 4 NH₃: \( 4 \times 17 = 68 \) g/mol
- Nitro (NO₂) = 46 g/mol
- Chlorine (Cl) = 35.5 g/mol, and there are 2 Cl: \( 2 \times 35.5 = 71 \) g/mol

Calculating the total molar mass:
\[ \text{Molar mass} = 59 + 68 + 46 + 71 = 244 \text{ g/mol} \]

### Step 3: Calculate the number of moles of the complex in solution
Using the mass of the complex dissolved:
\[ \text{Mass of complex} = 2.44 \text{ g} \]
\[ \text{Number of moles} = \frac{\text{Mass}}{\text{Molar mass}} = \frac{2.44 \text{ g}}{244 \text{ g/mol}} = 0.01 \text{ moles} \]

### Step 4: Determine the moles of AgCl formed
The weight of AgCl precipitate obtained is:
\[ \text{Weight of AgCl} = 1.435 \text{ g} \]
The molar mass of AgCl (Ag = 108 g/mol, Cl = 35.5 g/mol):
\[ \text{Molar mass of AgCl} = 108 + 35.5 = 143.5 \text{ g/mol} \]
Calculating the number of moles of AgCl:
\[ \text{Number of moles of AgCl} = \frac{1.435 \text{ g}}{143.5 \text{ g/mol}} \approx 0.01 \text{ moles} \]

### Step 5: Relate the moles of AgCl to the moles of the complex
From the reaction, we know that 1 mole of the complex gives 2 moles of Cl⁻ ions (since there are 2 Cl in the complex). Therefore:
\[ \text{Moles of Cl} = 0.01 \text{ moles of AgCl} \Rightarrow \text{Moles of complex} = \frac{0.01}{2} = 0.01 \text{ moles} \]

### Step 6: Name the complex
The naming convention for coordination compounds states that:
- The ligands are named first in alphabetical order.
- The number of ligands is indicated by prefixes (tetra- for 4, di- for 2).
- The metal is named last, with its oxidation state in Roman numerals.

Thus, the name of the complex \(\text{[Co(NH}_3\text{)}_4\text{Cl}_2\text{NO}_2]\) is:
**Tetraammine dichloronitrocobalt(III)**

### Final Answer
The name of the complex is **Tetraammine dichloronitrocobalt(III)**.

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