Correct option is C
Pentavalent impurities are those that have five valence electrons. These impurities are typically used to dope semiconductors to create n-type materials by providing extra electrons.
(a) Arsenic (As): Arsenic is a pentavalent element with five valence electrons. It is commonly used as an n-type dopant in semiconductors.
(b) Antimony (Sb): Antimony is also a pentavalent element with five valence electrons. It is another common n-type dopant.
(c) Indium (In): Indium is a trivalent element with three valence electrons. It is typically used as a p-type dopant in semiconductors, not as a pentavalent impurity.
(d) Phosphorus (P): Phosphorus is a pentavalent element with five valence electrons. It is frequently used as an n-type dopant.
The element that is NOT a pentavalent impurity is (c) Indium.
