(Points: 10) For the following:
i) HClO4 > HBrO4 > HIO4
ii) NH3 > PH3 > AsH3 > SbH3
iii) HOClO3 > HOClO2 > HOClO > HOCl
iv) HBr>HCl>HF
The order of acidity is correct for which series?
1. ) all are correct
2. ) ii and iii
3. ) ii and iv
4. ) ii
5. ) i, iii, iv
To determine the correct order of acidity for each series, we need to compare the strength of the acids involved. Here's how we can analyze each series:
i) HClO4 > HBrO4 > HIO4
To determine the acidity of these acids, we need to consider the strength of the conjugate bases. The key factor here is the electronegativity of the central atom in each acid. The central atom becomes more electronegative as we move from Cl to Br to I, resulting in stronger acidity. Therefore, the given order is correct.
ii) NH3 > PH3 > AsH3 > SbH3
In this series, we are comparing the strength of bases. The strength of a base is determined by the lone pair availability and size of the atom. As we move down the periodic table, the size of the atom increases, and the lone pair availability also increases. Therefore, the order given is correct.
iii) HOClO3 > HOClO2 > HOClO > HOCl
Similar to the first series, as the electronegativity of the central atom increases, the acidity of the acid increases. Here, the central atom is the same (chlorine), but the oxidation state of the chlorine atom increases. Higher oxidation states result in increased acidity. Therefore, the order given is correct.
iv) HBr > HCl > HF
In this series, we are comparing the strength of the acids. The strength of an acid is determined by the stability of its conjugate base. Here, as we move from fluorine to chlorine to bromine, the negative charge of the corresponding conjugate bases becomes more stable. Therefore, the order given is correct.
Now, let's analyze the options:
1) All are correct: This option indicates that all the given orders of acidity are correct. However, we have determined that the correct order is i) for the first series, ii) for the second series, iii) for the third series, and iv) for the fourth series. Therefore, this option is incorrect.
2) ii) and iii): This option suggests that the orders of acidity for the second and third series are correct. After analyzing the series, we have determined that both ii) and iii) are indeed correct. Therefore, this option is correct.
3) ii) and iv): This option suggests that the orders of acidity for the second and fourth series are correct. After analyzing the series, we have determined that both ii) and iv) are correct. Therefore, this option is also correct.
4) ii): This option suggests that only the order of acidity for the second series is correct. However, we have determined that the orders of acidity for both the second and third series are correct. Therefore, this option is incorrect.
5) i), iii), iv): This option suggests that the orders of acidity for the first, third, and fourth series are correct. After analyzing the series, we have determined that the orders of acidity for i), iii), and iv) are indeed correct. Therefore, this option is correct.
Therefore, the correct answer is option 5) i), iii), iv), where the orders of acidity for the first, third, and fourth series are correct.