The electron affinity values for each case are determined as follows:
(A) Be + e$^-$ $\to$ Be$^-$: Electron affinity is negative (E.A. = --ive).
(B) N + e$^-$ $\to$ N$^-$: Electron affinity is negative (E.A. = --ive).
(C) O + e$^-$ $\to$ O$^-$: Electron affinity is positive for O $\to$ O$^-$ (E.A. = +ive).
(D) Na + e$^-$ $\to$ Na$^-$: Electron affinity is positive (E.A. = +ive).
(E) Al + e$^-$ $\to$ Al$^-$: Electron affinity is positive (E.A. = +ive).
Thus, the correct answer is: A, B, and C only.
The portion of the line \( 4x + 5y = 20 \) in the first quadrant is trisected by the lines \( L_1 \) and \( L_2 \) passing through the origin. The tangent of an angle between the lines \( L_1 \) and \( L_2 \) is: