Q.Which of the following metals has the largest abundance in the earth’s crust?

Boron occurs in nature almost entirely as borate minerals -- its two chief commercial ores are borax, Na₂[B₄O₅(OH)₄].8H₂O, and kernite, Na₂[B₄O₅(OH)₄].2H₂O -- rather than as any free element or simple oxide.

Aluminium is the most abundant metal in the earth's crust (and the third most abundant element overall, after oxygen and silicon). It occurs as oxides and is locked into aluminosilicate rocks throughout the crust; it is extracted commercially from its chief ore, bauxite, Al₂O₃.2H₂O, via purification and electrolytic reduction. Aluminium's abundance and light weight are why it and its alloys are used so widely, from household utensils to aircraft parts -- and why duralumin, an aluminium alloy strengthened with copper, manganese and magnesium, is prize …