AP EAMCET202022 Sep 2020Morning ShiftChemistryClassification of Elements and Periodicity in PropertiesActual
In which of the following options order of arrangement does not agree with the variation of property indicated against it?
Options
- AAl ³⁺ < Mg ²⁺ < Na ⁺ < F (increasing ionic size)
- BB < C < O < N (increasing first ionisation enthalpy)
- Cl < Br < Cl < F (increasing electron gain enthalpy)
- DLi < Na < K < Rb (increasing metallic radius)
Correct answer
C. l < Br < Cl < F (increasing electron gain enthalpy)
Step-by-step solution
Electron gain enthalpy becomes less negative on moving down a group due to increase in atomic size. However, the electron gain enthalpy of F is less negative than CI due to electron-electron repulsion in small-sized F atom. Thus, the correct order is F Br > l . F , CI , Br and I have e_g H values (in kJ ^ Jmol I ⁻¹ ) -328,-349,-325 and -295 respectively. That order of arrangement does not agree with the variation of property. Hence, the correct option is (3).