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.
Which of the following oxidation state is common for all lanthanoids?

Options

A. `+2`
B. `+3`
C. `+4`
D. `+5`

Explanation

To answer the question regarding the common oxidation state of lanthanoids, we can follow these steps:

### Step 1: Understand the General Properties of Lanthanoids
Lanthanoids are a series of 15 elements from lanthanum (La) to lutetium (Lu) in the periodic table. They are known for their similar properties due to the filling of the 4f orbitals.

### Step 2: Identify the Common Oxidation State
The most common oxidation state for lanthanoids is +3. This is because, in most of their compounds, they lose three electrons from their outermost shells (4f and 6s).

### Step 3: Consider Exceptions
While +3 is the most common oxidation state, there are exceptions. Europium (Eu) and Ytterbium (Yb) can also exhibit a +2 oxidation state. However, this does not change the fact that +3 is the predominant oxidation state for the majority of lanthanoids.

### Step 4: Conclusion
Thus, the common oxidation state for all lanthanoids is +3, with the noted exceptions of Eu and Yb.

### Final Answer
The common oxidation state for all lanthanoids is +3.

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