The molecular formula of chloride of a metal M is `MCl_3`. The formula of its carbonate would be

Options

A. `MCO_(3)`
B. `M_(2)(CO_(3))_(3)`
C. `M_(2)CO_(3)`
D. `M(CO_(3))_(2)`

Explanation

To determine the molecular formula of the carbonate of the metal M, given that its chloride is MCl₃, we can follow these steps:

### Step 1: Determine the Valency of Metal M
From the formula MCl₃, we can deduce that the valency of metal M is +3. This is because each chlorine (Cl) has a valency of -1, and there are three chlorine atoms. Therefore, to balance the charges, M must have a +3 charge.

**Hint:** Look at the charges of the ions in the compound to find the valency of the metal.

### Step 2: Identify the Valency of the Carbonate Ion
The carbonate ion (CO₃) has a charge of -2. This is important for determining how many carbonate ions will combine with the metal M.

**Hint:** Remember the common charges of polyatomic ions like carbonate.

### Step 3: Set Up the Formula
Now we have:
- Valency of M = +3
- Valency of carbonate (CO₃) = -2

To combine these ions, we need to find the lowest common multiple of their charges. The least common multiple of 3 and 2 is 6.

**Hint:** Finding the least common multiple helps in balancing the charges when forming compounds.

### Step 4: Determine the Number of Each Ion Needed
To achieve a total charge of +6 from M and -6 from carbonate, we can use:
- 2 M ions (2 × +3 = +6)
- 3 carbonate ions (3 × -2 = -6)

### Step 5: Write the Formula
Combining the ions, we get:
- 2 M ions and 3 carbonate ions gives us the formula: M₂(CO₃)₃.

### Final Answer
Thus, the formula of the carbonate of metal M is **M₂(CO₃)₃**.

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