The given question requires identification of elements among the given list that do not belong to the lanthanoid series. The lanthanoids, also known as the lanthanides, consist of 15 elements ranging from atomic numbers 57 (Lanthanum, La) to 71 (Lutetium, Lu).
Let's evaluate each element in the list:
From this evaluation, we can see that the element Cm (Curium) is the only one that does not belong to the lanthanoid series.
Conclusion: The correct answer is option \(1\), as Cm (Curium) is the only element that is not a lanthanoid.
Among the given elements: - Eu (Europium), Er (Erbium), Tb (Terbium), Yb (Ytterbium), and Lu (Lutetium) all belong to the lanthanoid series. Cm (Curium) belongs to the actinide series.
Hence, the number of elements that do not belong to lanthanoids is 1 (Cm).
In the given figure, the blocks $A$, $B$ and $C$ weigh $4\,\text{kg}$, $6\,\text{kg}$ and $8\,\text{kg}$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is ___ N.
(Given: $g = 10\,\text{m s}^{-2}$) 
The equivalent resistance between the points \(A\) and \(B\) in the given circuit is \[ \frac{x}{5}\,\Omega. \] Find the value of \(x\). 
Method used for separation of mixture of products (B and C) obtained in the following reaction is: 