In the depletion region of a diode,(A) There are no mobile charges.(B…

The correct answer is Option (1) → (A), (C) and (D) only

When the junction forms, electrons and holes diffuse across it and recombine, leaving uncovered immobile ions (positive on the n-side, negative on the p-side) in a layer emptied of free carriers: the depletion region.

(A) There are no mobile charges. — Correct. The region is depleted of free electrons and holes; hence its name.

(B) An equal number of holes and electrons exist, making the region neutral. — Incorrect. The region is not neutral: its space charge, of opposite signs on the two sides, produces the barrier potential.

(C) Recombination of electrons and holes takes place. — Correct. Diffusing electrons and holes recombine there, which creates the depletion region.

(D) Immobile ions exist. — Correct. The ionised donors and acceptors are fixed in the crystal lattice.

NCERT (2026-27):
p-n Junction Formation – “… When an electron diffuses from n → p, it leaves behind an ionised donor on n-side. This ionised donor (positive charge) is immobile as it is bonded to the surrounding atoms.”

p-n Junction Formation – “… This space-charge region on either side of the junction together is known as depletion region as the electrons and holes taking part in the initial movement across the junction depleted the region of its free charges (Fig. 14.10).”

Summary – “… 12. p-n junction is the ‘key’ to all semiconductor devices. When such a junction is made, a ‘depletion layer’ is formed consisting of immobile ion-cores devoid of their electrons or holes. This is responsible for a junction potential barrier.”