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(i) Lithium forms monoxide with oxygen whereas sodium forms peroxide with oxygen why ? (ii) Write about the uses of strontium. |
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Answer» Solution :(i) 1. The fact that a small cation can stabilize a small anion and a large cation can stabilize a large anion explains the formation and stability of the oxides. 2. The size of `Li^(+)` ion is very small and it has a strng POSITIVE field around it. If can combine with only small anion `O^(2-)` ion, resulting in the formation of monoxide `Li_(2)O`. 3. The `Na^(+)` ion is a larger cation and has a week positive field around it and can stabilize a bigger peroxide ion, `O_(2)^(2-)` or `[-O-O-]^(2-)` resulting in the formation of peroxide `Na_(2)O_(2)`. (ii) 1. `.^(90)"Sr"` is used in cancer therapy. 2. `.^(87)"Sr"//.^(86)` Sr ratio is used in marine investigators as well in teeth, TRACKING animal migrations or in criminal forensics. 3. Dating of rocks. 4. Strontium is used as a radioactive tracer in dterminining the source of archaeological materials such as timbers and coins. |
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