In which one of the following arrangements the given sequence is not strictly according to the properties…

In which one of the following arrangements the given sequence is not strictly according to the properties indicated against it?

  1. HF<HCl<HBr<HI: Increasing acidic strength
  2. H2O<H2 S<H2Se<H2Te: Increasing pKa values
  3. NH3<PH3<AsH3<SbH3: Increasing acidic character
  4. CO2<SiO2<SnO2<PbO2: Increasing oxidizing power

Solution

1) HF<HCl<HBr<HI bond strength decreases therefore, acidic strength increases.
2) H2O<H2 S<H2Se<H2Te from going down the group bond length increase so bond strength decreases therefore, acidic nature of these will increase but pKa will decrease.
So, this given order is wrong.
3) NH3<PH3<AsH3<SbH3 from going down the group bond length increases, so bond strength decreases therefore, acidic nature of these will increase
4) CO2<SiO2<SnO2<PbO2 From going down the group stability of higher oxidation state decreases due to inert pair effect therefore, their tendency to reduce will increase, so their oxidizing power will increase.

Asked in: NEET 2021

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