Nickel and copper ores are generally sulfides, whereasaluminum ore is an oxide. Explain this observation on thebasis of the hard/soft acid/base concept.

Which set contains an acidic oxide, an amphoteric oxide, and a basic oxide, arranged in that order.          (A) CO2, SiO2, SnO2;          (B) BeO, Al2O3, SiO2;          (C) B2O3, Al2O3, Tl2O;          (D) Li2O, MgO, Ga2O3

Give the oxidation state of the metal for each of the following oxides of the first transition series. (Hint: Oxides of formula M3O4 are examples of mixed valence compounds in which the metal ion is present in more than oneoxidation state. It is possible to write these compound formulas in the equivalent format MO∙M2O3, to permit estimation of the metal’s two oxidation states.)(a) Sc2O3(b) TiO2(c) V2O5(d) CrO3(e) MnO2(f) Fe3O4(g) Co3O4(h) NiO(i) Cu2O

Many lithium salts are hygroscopic (absorb water), whereas the corresponding salts of the other alkali metals are not. Explain.

Silica (SiO2) is an impurity that must be removed from ametal oxide or sulfide ore when the ore is being reduced toelemental metal. To do this, lime (CaO) is added. It reactswith the silica to form a slag of calcium silicate (CaSiO3),which can be separated and removed from the ore.(a) Write the balanced equation for this process.(b) Can this be considered a Lewis acid–base reaction? Ifso, what is the Lewis acid and what is the Lewis base?

Which statement regarding oxides is true? O Amphoteric oxides behave as acidic oxides in the presence of H3O+ CaO is an acidic oxide because Ca acts as an acid CO₂ is an acidic oxide because CO₂ ionizes in H₂O and O²- acts as a Lewis acid. O None of the above statements are true about

Lithium salts are often much less soluble in water than the corresponding salts of other alkali metals. For example, at 188C, the concentration of a saturated LiF solution is 1.0x10-2 M,whereas that of a saturated KF solution is 1.6 M. How would you explain this behavior?

For each of the following groups, which metal would youexpect to have the highest melting point: (a) gold, rhenium,or cesium; (b) rubidium, molybdenum, or indium; (c) ruthenium,strontium, or cadmium?

Some metal oxides, such as Sc2O3, do not react with purewater, but they do react when the solution becomes eitheracidic or basic. Do you expect Sc2O3 to react when the solutionbecomes acidic or when it becomes basic? Write a balancedchemical equation to support your answer.

The only alkali metal that reacts with oxygen to give a compound with the expected stoichiometry is lithium,which gives Li2O.In contrast,soduim reacts with oxygen to give Na2O2,and the heavier alkali metals form superoxides.Explain the difference in stoichiometries of these products