Read the passage given below and answer the following questions:
Although actinoids are similar to lanthanoids in that their electrons fill the 5f orbitals in order, their chemical properties are not uniform and each element has characteristic properties. Promotion of 5 - 6d electrons does not require a large amount of energy and examples of compounds with 77 acid ligands are known in which all the 5f, 60, 7s, and 7p orbitals participate in bonding. Trivalent compounds are the most common, but other oxidation states are not uncommon. Especially, thorium, protactinium, uranium, and neptunium tend to assume the +4 or higher oxidation state.
General electronic configuration of actinoids is `(n-2)f^(1-14) (n - 1)d^(0-2) ns^2`. Which of the following actinoids have one electron in 6d orbital?

Options

A. U (Atomic no. 92)
B. Np (Atomic no.93)
C. Pu (Atomic no. 94)
D. Bk (Atomic no. 97)

Explanation

To determine which actinoids have one electron in the 6d orbital, we need to analyze the electronic configurations of the actinoids based on their atomic numbers. The general electronic configuration for actinoids is given as `(n-2)f^(1-14) (n-1)d^(0-2) ns^2`.

Let's break down the steps to find the answer:

### Step 1: Identify the Atomic Numbers
The actinoids we need to consider are:
1. Uranium (U) - Atomic number 92
2. Neptunium (Np) - Atomic number 93
3. Plutonium (Pu) - Atomic number 94
4. Berkelium (Bk) - Atomic number 97

### Step 2: Write the Electronic Configurations
Using the atomic numbers, we can write the electronic configurations for each actinoid:

1. **Uranium (U)**:
- Atomic number: 92
- Configuration: [Rn] 5f³ 6d¹ 7s²
- Here, there is 1 electron in the 6d orbital.

2. **Neptunium (Np)**:
- Atomic number: 93
- Configuration: [Rn] 5f⁴ 6d¹ 7s²
- Here, there is also 1 electron in the 6d orbital.

3. **Plutonium (Pu)**:
- Atomic number: 94
- Configuration: [Rn] 5f⁶ 7s²
- Here, there are no electrons in the 6d orbital.

4. **Berkelium (Bk)**:
- Atomic number: 97
- Configuration: [Rn] 5f⁹ 7s²
- Here, there are no electrons in the 6d orbital.

### Step 3: Conclusion
From the electronic configurations, we can conclude that the actinoids that have one electron in the 6d orbital are:
- **Uranium (U)**
- **Neptunium (Np)**

### Final Answer
The actinoids that have one electron in the 6d orbital are Uranium (U) and Neptunium (Np).

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