The compound(s) that is (are) removed as slag during the extraction of copper is :

(A) CaO

(B) FeO

(C) Al₂O₃

(D) ZnO

(E) NiO

Choose the correct answer from the options given below:

The reaction of $$\mathrm{H}_{2} \mathrm{O}_{2}$$ with potassium permanganate in acidic medium leads to the formation of mainly :

Choose the correct order of density of the alkali metals :

The geometry around boron in the product 'B' formed from the following reaction is

$$ \begin{aligned} &\mathrm{BF}_{3}+\mathrm{NaH} \stackrel{450 \mathrm{~K}}{\rightarrow} \mathrm{A}+\mathrm{NaF} \\\\ &\mathrm{A}+\mathrm{NMe}_{3} \rightarrow \mathrm{B} \end{aligned} $$