Here you can share with our editor and volunteers any comments, suggestions, or corrections you have after reviewing the annotated solutions shared on the USNCO Exams Page.
Please start your comment with the exam and year you are referencing - i.e. Local 2020, National 2019.
For question 50 on the 2017 national Part I exam, the exam annotations indicate that for part (B) the molecule whose Lewis structure is shown is C2H4, when the problem states that the comparison is between C2H6 and B2H6. The annotations give the correct answer, it's just that the different Lewis structure compared to the test answer might confuse some people.
A few typos were found in national 2020 annotation by a reader as follows, thanks!
typo in 2019 national from reader, thank you!
Hi Dr. Chen, I see a typo in 2019 National #6. The volume of acid should be 45 + 50 + 55 = 150 so the molarity should be .0967 M. The solutions had 45 + 50 + 55 = 145, which isn't a big deal but it is a typo