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JEE Main levelSingle correct optionDifficulty 2 of 3pt139

Nitrogen has a much less negative (nearly zero) electron gain enthalpy than carbon mainly because

Athe added electron would have to pair up in a half-filled, stable $2 p^{3}$ subshell of nitrogen
Bnitrogen has a lower nuclear charge than carbon
Ccarbon has a completely filled $2 p$ subshell
Dnitrogen has a larger atomic radius than carbon

Answer: A

N

(

2 s^{2} 2 p^{3}

) has an extra-stable half-filled

2 p

set. An incoming electron must pair in one of these orbitals and suffer repulsion. In carbon (

2 p^{2}

) the electron can enter an empty

2 p

orbital, giving about

- 122 kJ mo l^{- 1}

.

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