Metallic character refers to the ability of an element to lose electrons and form positive ions. As we move down a group in the periodic table, the atomic size increases, and the outer electrons are further from the nucleus, making it easier for the element to lose electrons. This results in an increase in metallic character down a group. On the other hand, as we move from left to right across a period, the atomic size decreases, and the effective nuclear charge increases, making it harder for the element to lose electrons.
Therefore, metallic character decreases across a period from left to right. Among the given elements: Potassium (K) is an alkali metal located in Group 1, and it is farthest to the left and down the group. Therefore, it has the highest metallic character. Silicon (Si), being a metalloid in Group 14, has a lower metallic character compared to metals. It is further to the right and higher in the period, so it has the least metallic character among the elements listed. So, the correct sequence is \(Si < Be < Mg < K\).
Method used for separation of mixture of products (B and C) obtained in the following reaction is: 
MX is a sparingly soluble salt that follows the given solubility equilibrium at 298 K.
MX(s) $\rightleftharpoons M^{+(aq) }+ X^{-}(aq)$; $K_{sp} = 10^{-10}$
If the standard reduction potential for $M^{+}(aq) + e^{-} \rightarrow M(s)$ is $(E^{\circ}_{M^{+}/M}) = 0.79$ V, then the value of the standard reduction potential for the metal/metal insoluble salt electrode $E^{\circ}_{X^{-}/MX(s)/M}$ is ____________ mV. (nearest integer)
[Given : $\frac{2.303 RT}{F} = 0.059$ V]
An infinitely long straight wire carrying current $I$ is bent in a planar shape as shown in the diagram. The radius of the circular part is $r$. The magnetic field at the centre $O$ of the circular loop is :
