17.An element X on reacting with oxygen forms XO2. The oxide when dissolved in water turned red litmus blue. What will be the nature of ‘X’? Give reason for your answer.

The oxide is basic, X must be a group two metal

Explanation:

The oxide XO2 must be an inorganic peroxide of a group two element. Inorganic peroxides of group two elements are highly basic because they dissolve in water to yield the corresponding metal hydroxides. These metal hydroxides are strongly basic solutions with a very high pH. Hence X may be Calcium, magnesium, barium, strontium or radium.

Group two metal peroxides include; CaO2, MgO2,BaO2 etc. They all dissolve in water to give corresponding basic solutions. For instance, calcium peroxide reacts with water as follows; CaO2 (s) + 2H2O(l) >Ca(OH)2(aq) + H2O2(aq). The production of Ca(OH)2 makes the solution basic. The hydrogen peroxide produced decomposes to water and oxygen.

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