Which of the following elements is a metalloid? MCQ with Answer and Explanation

Explanation:
Roasting is the process of heating the concentrated ore (usually sulfide ores) strongly in the presence of excess air below its melting point. It converts the ore to its oxide form and removes volatile impurities as gases (e.g., 2ZnS + 3O₂ → 2ZnO + 2SO₂).

Explanation:
Valence electrons are the electrons in the outermost shell. Configuration 2,8,2 means K=2, L=8, M=2. The outermost shell M has 2 electrons, so valency is 2, typical of Group 2 metals (Mg). These atoms lose 2 electrons to form M²⁺. The number of valence electrons determines the group in the periodic table. Elements with 2 valence electrons belong to Group 2 (alkaline earth metals).

Explanation:
Acids turn blue litmus red; bases turn red litmus blue. Litmus is a natural indicator from lichens, purple in neutral solution.