alleryStart learning →A quadratic solved for an equilibrium change gives two roots. How is the unwanted one recognised?
AIt is always the larger of the two roots
BIt is always the root nearer to zero in size
CIt is the root that is not a whole number
DIt is the root that gives a negative amount
Answer & Solution
Correct answer: D. It is the root that gives a negative amount
1. A quadratic yields two roots, but only one can describe a real mixture.
2. The test is physical, not algebraic: concentrations can never come out negative.
3. A root that would drive a product concentration below zero is the extraneous root.
4. Size alone does not decide it, since the acceptable root may be the larger or the smaller.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 13 "Fundamental Equilibrium Concepts", section 13.4 Equilibrium Calculations_
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