Number of identical Cr-O bonds in dichromate ion `Cr_(2)O_(7)^(2-)` is :

Options

A. 4
B. 6
C. 7
D. 8

Answer

To determine the number of identical Cr-O bonds in the dichromate ion \( \text{Cr}_2\text{O}_7^{2-} \), we can follow these steps:

### Step 1: Understand the Structure of Dichromate Ion
The dichromate ion consists of two chromium (Cr) atoms and seven oxygen (O) atoms. The overall charge of the ion is -2.

### Step 2: Draw the Lewis Structure
To visualize the bonding, we need to draw the Lewis structure of the dichromate ion. In this structure, we will place the two chromium atoms in the center and surround them with the seven oxygen atoms.

### Step 3: Identify the Bonds
In the Lewis structure, we will identify the types of bonds formed between the chromium and oxygen atoms. The dichromate ion typically has a structure where there are six terminal oxygen atoms bonded to the chromium atoms and one oxygen atom that is shared between the two chromium atoms.

### Step 4: Count the Identical Cr-O Bonds
In the structure of the dichromate ion, we find that there are six terminal Cr-O bonds that are equivalent due to resonance. This means that the bonds can be represented as having the same bond character.

### Step 5: Conclusion
Thus, the number of identical Cr-O bonds in the dichromate ion \( \text{Cr}_2\text{O}_7^{2-} \) is 6.

### Final Answer
The number of identical Cr-O bonds in the dichromate ion \( \text{Cr}_2\text{O}_7^{2-} \) is **6**.

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