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InterviewSolution
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Which of the following elements from amphoteric oxides?A. `N` and `P`B. `P` and `As`C. `As` and `Sb`D. `Sb` and `Bi` |
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Answer» Correct Answer - 3 Group `15` shows the usual trend, that metallic character increases in decending the group. Thus first two elements `N` and `P`, are nonmetal,`As` and `Sb` are metallodis,Which show metallic as well as nonmetallic properties and `Bi` is a true metal. The increaseing metallic character is shown by the following features. A. In the appearence and structures of the elements: nitrogen is a colourless gas ,phosphorus is a white, Waxy solid while rest of the elements are brittle ,metallic solids. B. By their tendency to form positive ions:only antimony and bismuth can from the `3-`valent cation`E^(3+).` C. By the nature of their oxides: nonmetallic oxides are acidic, metallodic oxides are amphoteric and metallic oxides are typically basic. Thsu the normal oxide of `N` and `P(N_(2)O_(3),P_(4)O_(6))`are stongly acidic, whereas those of `As` and `Sb(As_(4)O_(6), Sb_(4)O_(6))` are amphoteric and that of `Bi(Bi_(2)O_(3))` is largly basic. Antimony (III) oxide, being amphoteric dissolves in sodium hydroxide solution to form an antimontie (III) and in concentrated sulphuric acid to give a sulphate: `Sb_(4)O_(6)(s)+4OH^(-)(aq. )rarr4SbO_(2)^(-)(aq.)+2H_(2)O(l)` `Sb_(4)O_(6)(s)+6H_(2)SO_(4)(l)rarr4Sb_(2)(SO_(4))_(3)(a.q)+6H_(2)O(l)` D.The electrical resistivity of a metallic forms `(alpha-As 33, alpha-Sb 39` and `alpha-Bi 106 mu` ohm cm) are much lower than for white`P(1xx10^(17)mu" ohm cm")`, indicating an increase in metallic properties. However, the resistivity values are higher than the values for a good conductor such as `Cu, 1.67 mu" ohm cm")` and higher than,`Sn, 11`, and `Pb, 20 mu` ohm cm, in the adjancent group. |
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