Total number of Cr–O bonds in Chromate ion and dichromate ion is.

Answer

To determine the total number of Cr–O bonds in chromate ion (CrO4^2-) and dichromate ion (Cr2O7^2-), we will analyze each ion separately.

### Step 1: Analyze the Chromate Ion (CrO4^2-)
1. The chromate ion has the formula CrO4^2-.
2. In the chromate ion, chromium (Cr) is bonded to four oxygen (O) atoms.
3. The structure of the chromate ion can be represented as follows:
- One Cr atom is centrally located, and it forms single bonds with three O atoms and a double bond with one O atom.
4. Therefore, the total number of Cr–O bonds in the chromate ion is 4.

### Step 2: Analyze the Dichromate Ion (Cr2O7^2-)
1. The dichromate ion has the formula Cr2O7^2-.
2. In the dichromate ion, there are two chromium (Cr) atoms and seven oxygen (O) atoms.
3. The structure of the dichromate ion can be represented as follows:
- Each Cr atom is bonded to three O atoms, with one of the O atoms being shared between the two Cr atoms (forming a double bond).
4. Therefore, the total number of Cr–O bonds in the dichromate ion is 6 (3 bonds from each Cr atom, and one shared bond).

### Step 3: Calculate the Total Number of Cr–O Bonds
1. From the chromate ion, we have 4 Cr–O bonds.
2. From the dichromate ion, we have 6 Cr–O bonds.
3. Adding these together gives us:
- Total Cr–O bonds = 4 (from chromate) + 6 (from dichromate) = 10.

### Final Answer
The total number of Cr–O bonds in chromate ion and dichromate ion is **10**.

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