Which of the following pairs of elements would have a more negative electron gain enthalpy? i) O or N ii) F or Cl

The negative electron gain enthalpy of F is less/more than Cl.

Which of the following will have the most negative electron gain enthalpy and which the east negative? (P, S, CI, F). Explain your answer.

Which of the following element has maximum electron gain enthapy(negative)? F , Cl , Br , I .

Because of lanthanoid contraction, which of the following pairs of elements have nearly same atomic radii? (Numbers in the parenthesis are atomic numbers)

Halogens have maximum negative electron gain enthalpy in the respective periods of the periodic table. Why ?

Which of the following pairs of sets are disjoint:- { a, e, i, o, u } and { c, d, e, f}