Statement I is correct because the 4f and 5f series (lanthanides and actinides) are placed separately to maintain the structure of the Periodic Table. However, Statement II is incorrect, as s-block elements are highly reactive and are generally found in combined states in nature.
Which one of the following elements is found in the free state in nature?
What is the total no. of rare earth metals:
Let $ P_n = \alpha^n + \beta^n $, $ n \in \mathbb{N} $. If $ P_{10} = 123,\ P_9 = 76,\ P_8 = 47 $ and $ P_1 = 1 $, then the quadratic equation having roots $ \alpha $ and $ \frac{1}{\beta} $ is: