# concentrations of unknown A, B, C were [singular or plural?]

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#### jiangr

##### New Member
Hello
I' m writing a lab report and here comes a sentence I'm going to write but I'm not sure the grammar here
A. The concentrations of unknown A, B, C were 0.186, 0.199 and 0.021 respectively, which were calculated from measured absorbances.
B. The concentration of unknown A, B, C were 0.186, 0.199 and 0.021 respectively, which were calculated from measured absorbances. OR
C. The concentration of unknown A, B, C was 0.186, 0.199 and 0.021 respectively, which was calculated from measured absorbance.

THANKS

• #### Procol

##### Senior Member
Hello

A. is fine.
B. should read "the concentration of unknown A, B, C was 0.186, 0.199 and 0.021 respectively, which were calculated from measured absorbances"
C. T
he concentration of unknown A, B, C was 0.186, 0.199 and 0.021 respectively, which were calculated from measured absorbance.
If i doubt, use A.

#### Cenzontle

##### Senior Member
I'm with Procol, your sentence A is good.
Inside sentence A, don't you want to say "A, B, and C" (as you did with the numbers)?

#### safienwijon

##### New Member
I'm with Procol, your sentence A is good.
Inside sentence A, don't you want to say "A, B, and C" (as you did with the numbers)?
I agree with the addition of "and" between "B" and "C" (no pun intended ).

Side note: I very rarely find literature where the correct punctuation in commas is used for listings. I frequently see 1,2 and 3 as opposed to 1,2, and 3 which is frustrating. Am I wrong? Should it not be 1,2, and 3? If I put "2 and 3" does that not create a grouping of "2" and "3"? I always thought the commas were creating a separation of each item, or in this example, number.

#### pob14

##### Senior Member
Safienwijon, if you search this forum (or the internet in general) for "Oxford comma" or "Harvard comma," you will find many, many opinions about your question.

#### jiangr

##### New Member
Thank you all guys. I would stay on option A and will add an "and" which was forgotten as I posted this question in a rush

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