Question
In Which of the following arrangement, the given sequence is not strictly according to the property indicated against it ?
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HF < HCl< HBr < HI : increasing acidic strength
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H2O < H2S < H2Se < H2Te : increasing pKa values.
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NH3 < PH3 < AsH3 < SbH3 : increasing acidic character
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CO2 < SiO2 < SnO2 <PbO2 : increasing oxidising power
Solution
B.
H2O < H2S < H2Se < H2Te : increasing pKa values.
(a,c) As we move from top to bottom in a group, the acidic strength of hydrides increases. Therefore, order of acidic strength of hydrides of VA and VII A group elements is
NH3 < PH3 < AsH3< SbH3
HF<HCl < HBr <HI
b) As we move from top to bottom in a group acidic nature (Ka) increases. Therefore, pKa decreases. Thus, order of pKa value of hydrides of VI A group elements is
H2O > H2S >H2Se > H2Te
d) On moving from top to bottom, oxidising power of oxides increases. Thus, order of oxidising power of oxides of IVA group elements is
CO2 < SiO2 < SnO2 < PbO2
H2O > H2S >H2Se > H2Te
d) On moving from top to bottom, oxidising power of oxides increases. Thus, order of oxidising power of oxides of IVA group elements is
CO2 < SiO2 < SnO2 < PbO2
