Return to MCAT® Blog
Homepage
MCAT Physics Question — Uranium
- by
- Sep 01, 2014
- MCAT Question of the Day
- Reviewed By: Liz Flagge
Uranium, U-235, undergoes beta decay giving off an electron. The resulting atom is:
a) Th-231
b) Pa-235
c) Np-235
d) U-234
Explanation
In beta decay, an electron and a proton are created from a neutron. The electron is expelled leaving an atom with an increased atomic number and the same mass number. Remember: atomic number is the number of protons and mass number is the sum of protons and neutrons. Uranium, U-235, undergoes beta decay giving off an electron. The resulting atom has the same mass number, 235, and an atomic number increased by 1 to 93. The answer is Np-235.
a) Th-231, incorrect, This is the result of alpha decay losing a helium nucleus.
b) Pa-235, incorrect, Pa-235 results from positron emission when a proton becomes a neutron.
c) Np-235, correct.
d) U-234, incorrect, U-234 indicates loss of a neutron and decreased mass number. This does not occur because a proton is created leaving the mass number the same as before the decay.
Want more MCAT practice?
We’ve got options for every schedule and learning style!
From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!
Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.
Related Posts
Search the Blog
Free Consultation
Interested in our Online MCAT Course, One-on-One MCAT Tutoring or Med admissions packages? Set up a free consultation with one of our experienced Senior Student Advisors.
Schedule NowPopular Posts
-
-
MCAT Blog What's on the MCAT? -
-
-
MCAT Blog How to Review MCAT Full Lengths
Free MCAT Practice Account
Need great MCAT practice?Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.
Learn More