NEET2021Chemistryp Block Elements (Group 15, 16, 17 & 18)Actual
In which one of the following arrangements the given sequence is not strictly according to the properties indicated against it?
Options
- AHF < HCl < HBr < HI : Increasing acidic strength
- BH 2 O < H 2   S < H 2 Se < H 2 Te : Increasing pK a values
- CNH 3 < PH 3 < AsH 3 < SbH 3 : Increasing acidic character
- DCO 2 < SiO 2 < SnO 2 < PbO 2 : Increasing oxidizing power
Correct answer
B. H 2 O < H 2   S < H 2 Se < H 2 Te : Increasing pK a values
Step-by-step solution
1 ) HF < HCl < HBr < HI bond strength decreases therefore, acidic strength increases. 2 ) H 2 O < H 2   S < H 2 Se < H 2 Te from going down the group bond length increase so bond strength decreases therefore, acidic nature of these will increase but pK a will decrease. So, this given order is wrong. 3 ) NH 3 < PH 3 < AsH 3 < SbH 3 from going down the group bond length increases, so bond strength decreases therefore, acidic nature of these will increase 4 ) CO 2 < SiO 2 &