Lanthanides and actinides belong to ___________ block of the periodic table.

Explanation

To determine the block of the periodic table to which lanthanides and actinides belong, we can follow these steps:

### Step 1: Understand the Electronic Configuration of Lanthanides
- The general electronic configuration for lanthanides is given as:
\[ 4f^{1-14} \, 5d^{0-1} \, 6s^2 \]
- In this configuration, the last electron enters the 4f orbital.
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