SiO2 is the only possible choice because the other formulas contain metals. how do we know this? because the other formulas contain elements located on the left of the “staircase” on the periodic table that separates metals from non-metals.
Answer:
1. Lewis acid: F. Fe₃⁺, Lewis base: B. CN⁻
2. Lewis acid: A. AlCl₃, Lewis base: D. Cl⁻
3. Lewis acid: C. AlBr₃, Lewis base: E. NH₃
Hope this helps.
I think to measure the age of the rock