To solve this problem, we need to analyze each option based on the given property.$\\$Option 1: $$HF < HCl < HBr < HI : Increasing acidic strength$\\$• The acidic strength of hydrogen halides increases down the group in the periodic table.$\\$• This is because the bond strength decreases from HF to HI, making it easier to donate a proton.$\\$• Therefore, this sequence is correct.$\\$Option 2: $$H$_2$O$<$H$_2$S$<$H$_2$Se$<$H$_2$Te$$ : Increasing $pK_a$ values$\\$• $pK_a$ is inversely related to acidic strength; lower $pK_a$ means stronger acid.$\\$• The acidic strength of hydrides increases down the group, so $pK_a$ should decrease.$\\$• Therefore, the sequence should be $$H$_2$O$>$H$_2$S$>$H$_2$Se$>$H$_2$Te$$ for increasing $pK_a. \\$• This sequence is incorrect as given.$\\$Option 3: $$NH$_3 <$PH$_3 <$AsH$_3 <$SbH$_3$ : Increasing acidic character$\\$• The acidic character of group 15 hydrides increases down the group.$\\$• This is due to the decreasing bond strength and increasing size of the central atom.$\\$• Therefore, this sequence is correct.$\\$Option 4: $$CO$_2 <$SiO$_2 <$SnO$_2 <$PbO$_2$ : Increasing oxidizing power$\\$• The oxidizing power of oxides generally increases down the group.$\\$• This is because heavier elements can stabilize higher oxidation states more easily.$\\$• Therefore, this sequence is correct.$\\$Conclusion:$\\$The sequence in Option 2 is not strictly according to the properties indicated.$\\$Therefore, the correct answer is Option 2.