`[A(CO)_(x)]`
Here atomic number of A = 42. Find x.

Explanation

To find the value of \( x \) in the complex \( [A(CO)_{x}] \) where the atomic number of \( A \) is 42, we will follow these steps:

### Step 1: Identify the Element
The atomic number 42 corresponds to the element Molybdenum (Mo). Therefore, we can rewrite the complex as \( [Mo(CO)_{x}] \).

### Step 2: Determine the Effective Atomic Number (EAN)
The Effective Atomic Number (EAN) can be calculated using the formula:
\[
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