Which has least ionization potential?

Which of the following has the least ionization potential ?

Which of the following has the least ionization potential ?

The energy required to pull the most loosely bound electrons from an atom is known as ionization potential. It is expressed in electron volts. The value of ionization potential depends on three factors :(i) the charge on the nucleus (ii) the atomic radius and (iii) the screening effect of inner electron shells. Which of the following elements has the least ionization potential?

Which one has least ionisation potential?

Which of the following has least ionisation potential

Which of the following has highest ionization potential?

Which of the following has highest ionization potential?

Which of the following has highest ionization potential?