question_answer

The atomic numbers of vanadium (V), chromium (Cr), manganese (Mn) and iron (Fe) are respectively 23, 24, 25 and 26. Which one of these may be expected to have the highest second ionisation enthalpy?     AIEEE  Solved  Paper-2003

A)                         V                            

B) Cr                           

C) Mn                        

D) Fe

Correct Answer: B

Solution :

Write the electronic configuration of all the given metals according to Hund's and Pauli exclusion rules. Find the stability of metal after ejection of one electron.                                                                                 (by first IP) This is stable EC hence formation of \[C{{r}^{2+}}\] by second IP requires maximum enthalpy.