BMAT similar questions chemistry

Which of the following pairs have the same electronic configuration?

Answer is 2,4
But I cannot understand this answer

Make sure you know the atomic number of each element stated which will be the number of electrons when the element is uncharged. So when it is positively charged it gave out electrons (subtracted) and when it is negatively charged it accepts electrons (added)

  1. Li+ → 3 -1 =2 and Na+ → 11 -1 = 10 so it is wrong
  2. Mg2+ → 12-2 = 10 and Ne → 10 so it is correct.

You already found the answer by here but for the sake of practice:

  1. Na2+ → 11-2=9 and Ne → 10 so it is wrong
  2. O2- → 8+2 = 10 and C = 6 so it is wrong there may be a problem with the mark scheme

Although they’ll probably prove you with the atomic numbers its best to memorise group 1 group 2 and group 17 atomic numbers as well as carbon oxygen etc. as they’re pretty common to come up for the IMAT exam.

Hope this helped!


Thank you. I think 4 is wrong, too. But answer said correct. Do you think there is wrong in answer??

Yes I believe so, I’ve seen other mistakes too so. Also it wouldn’t make sense if it was right