JEE Main2013ChemistryClassification of Elements and Periodicity in PropertiesActual
Which of the following represents the correct order of increasing first ionization enthalpy for Ca , Ba , S , Se and Ar ?
Options
- ABa < Ca   < Se < S < Ar
- BCa   < Ba < S < Se < Ar
- CCa < S < Ba < Se < Ar
- DS < Se < Ca < Ba < Ar
Correct answer
A. Ba < Ca   < Se < S < Ar
Step-by-step solution
Ba   <   Ca   <   Se   <   S   <   Ar Ba and Ca belong to group IIA ( alkaline earth metals). Se and S belong to group Vl A (Chalcogens) and as we go down the group ionization enthalpy decreases with increasing atomic size. So,   Ba   <   Ca       and    Se   <   S Ar has stable completely filled electronic configuration and, therefore, has the highest ionization enthalpy.Hence, the correct order is Ba