GChem Absorbance Question

[HopefulOncoDoc]

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Hey everyone I'm having a little trouble with this question..

After a 0.100M solution of Cation A is passed through an ion exchange column with 90% efficiency, the new cation, Cation B, has an absorbance at lambda = 600nm that is twice as intense as Cation A. By what percent does the new absorbance differ from the initial absorbance?

A. The new absorbance is 55% less than the initial.
B. The new absorbance is 45% less than the initial.
C. The new absorbance is 90% greater than the initial.
D. The new absorbance is 111% greater that the initial.

The answer is C.

Thanks a lot everyone!

 

[loveoforganic]

Ok, you're exhanging cation A for cation B. Cation B has twice the molar absorbance of cation A. This means your absorbance is going to go up, rule out A and B. For the answer to be D (greater than 2x original absorbance), you would have to exchange more ions than you have, impossible. Choice C is left.