Consider the following statements regarding the properties of the 3 d transition series elements: Statement I: The increase in first ionization enthalpy across the 3 d series is less steep compared to the p-block elements of the same period. Statement II: The added 3 d electrons effectively shield the outer 4 s electrons, leading to a decrease in effective nuclear charge across the series. Statement III: The first io

Step-by-step solution

Statement I is true: in the 3 d series, electrons are added to the inner 3 d subshell, which partially shields the outer 4 s electrons from the increasing nuclear charge. This makes the increase in ionization enthalpy more gradual compared to p-block elements where electrons are added to the outermost shell. Statement II is false: d-electrons provide poor shielding, which causes the effective nuclear charge to increase across the series, not decrease. Statement III is true: compared to Group 2 metals, 3 d elements