An anion X- contains 45 neutrons and 36 electrons. What are the mass number, period number, and physical state under standard conditions of the neutral element X?

Match the periodic properties (List-I) with their correct trends across periods or groups (List-II): List-I A. Ionization enthalpy B. Metallic character C. Electron gain enthalpy (highest negative to lowest) D. Electronegativity List-II I. P < Si < Mg < Na II. I < N < O < F III. B < Be < C < O < N IV. I < Br < F < Cl

Arrange the following isoelectronic species in increasing order of their ionic radii: C4-, N3-, F-, O2-