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NEET levelSingle correct optionDifficulty 1 of 3ec048

For a spontaneous cell reaction under standard conditions, the correct combination is

A $E_{cell}^{\circ} > 0$ and $Δ_{r} G^{\circ} < 0$
B $E_{cell}^{\circ} > 0$ and $Δ_{r} G^{\circ} > 0$
C $E_{cell}^{\circ} < 0$ and $Δ_{r} G^{\circ} < 0$
D $E_{cell}^{\circ} < 0$ and $Δ_{r} G^{\circ} > 0$

Answer: A

Δ_{r} G^{\circ} = - n F E_{cell}^{\circ}

with

n

and

F

positive, so

E_{cell}^{\circ}

and

Δ_{r} G^{\circ}

always have opposite signs. A spontaneous reaction has

Δ_{r} G^{\circ} < 0

, hence

E_{cell}^{\circ} > 0

. Option D describes a non-spontaneous (electrolytic) reaction.

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