WCU CHEM 280 Final Exam Questions with Verified
Answers |2026/2027 Update | A+ Graded
A patient having radiotherapy uses radioactivity to kill infected cells while trying to minimize the
effect on the healthy cells. (T/F) - Answer -TRUE
Radioactive elements are used for:
A) medical diagnosis.
B) medical treatment.
C) determining age of fossils and rocks.
D) generating electricity.
E) all of the above - Answer -E) All of the above
Who discovered radioactivity? - Answer -Antoine Becquerel
How was radioactivity discovered? - Answer -Becquerel was studying X-rays and
phosphorescence to see if they were related.
Which of the following isotopes contains the most number of neutrons? - Answer -177/86Rn
1|Page
,How many protons and neutrons are in 34/16S? - Answer -16 p and 18 n
In a nuclear equation:
A) the daughter nuclide appears on the right-side of the arrow.
B) the sum of the atomic numbers on both sides must be equal.
C) the sum of the mass numbers on both sides must be equal.
D) all of the above
E) none of the above - Answer -D) all of the above
The first experiment that converted one element to another was performed in 1919 by Ernest
Rutherford. An isotope of nitrogen was bombarded with a type of particle to get an oxygen
atom as shown:
14/7 N + ? → 17/8 O + 1/1 H
Which type of particle was used to bombard the nitrogen atom? - Answer -alpha
If the 232/90 Th isotope emits an alpha particle, what would be the atomic number of the
resulting atom? - Answer -88
What happens to the mass number of a nucleus that emits an alpha particle? - Answer -It
decreases by four.
2|Page
,What is the missing particle?
231/90 Th ---> ____________ + 231/89 Ac - Answer -positron
What is the main product when 232/90 Th undergoes beta decay? - Answer -232/91 Pa
What is the main product when 235/92 U undergoes beta decay? - Answer -235/93 Np
What type of radioactive decay produces a daughter nuclide that is the same element as the
parent nuclide? - Answer -gamma
What is the main product when 249/97 Bk emits a gamma ray? - Answer -249/97 Bk
Which type of particle can be emitted by an unstable nucleus?
A) 4/2 He
B) 0/+1 e
C) 0/-1 e
D) all of the above
E) none of the above - Answer -D) all of the above
A Geiger-Muller counter detects radioactivity by: - Answer -ionization of argon gas in a chamber
which produces an electrical signal.
3|Page
, A scintillation counter detects radioactivity by: - Answer -emission of light from a NaI crystal
when radioactivity passes through the crystal.
If the half-life of a radioactive isotope is 32 days, how many half-lives must pass before a 3.0
gramsample is less than 0.03 grams? - Answer -7
Tritium ( 3/1 H ) is an isotope of hydrogen that is sometimes used to make the hands of watches
glow in the dark. The half-life of tritium is 12.3 years. After 49 years, approximately how much
of the original tritium remains? - Answer -6.25%
If an object has 6.25% of the C-14 (t-1/2 = 5,720 years) activity as a living organism, the age of
the item is: - Answer -22,920 years.
If an object has 25% of the C-14 (t-1/2 = 5,720 years) activity as a living organism, the age of the
- Answer -11,460 years.
The first person to artificially cause a nucleus to undergo a fission reaction was: - Answer -Enrico
Fermi.
4|Page
Answers |2026/2027 Update | A+ Graded
A patient having radiotherapy uses radioactivity to kill infected cells while trying to minimize the
effect on the healthy cells. (T/F) - Answer -TRUE
Radioactive elements are used for:
A) medical diagnosis.
B) medical treatment.
C) determining age of fossils and rocks.
D) generating electricity.
E) all of the above - Answer -E) All of the above
Who discovered radioactivity? - Answer -Antoine Becquerel
How was radioactivity discovered? - Answer -Becquerel was studying X-rays and
phosphorescence to see if they were related.
Which of the following isotopes contains the most number of neutrons? - Answer -177/86Rn
1|Page
,How many protons and neutrons are in 34/16S? - Answer -16 p and 18 n
In a nuclear equation:
A) the daughter nuclide appears on the right-side of the arrow.
B) the sum of the atomic numbers on both sides must be equal.
C) the sum of the mass numbers on both sides must be equal.
D) all of the above
E) none of the above - Answer -D) all of the above
The first experiment that converted one element to another was performed in 1919 by Ernest
Rutherford. An isotope of nitrogen was bombarded with a type of particle to get an oxygen
atom as shown:
14/7 N + ? → 17/8 O + 1/1 H
Which type of particle was used to bombard the nitrogen atom? - Answer -alpha
If the 232/90 Th isotope emits an alpha particle, what would be the atomic number of the
resulting atom? - Answer -88
What happens to the mass number of a nucleus that emits an alpha particle? - Answer -It
decreases by four.
2|Page
,What is the missing particle?
231/90 Th ---> ____________ + 231/89 Ac - Answer -positron
What is the main product when 232/90 Th undergoes beta decay? - Answer -232/91 Pa
What is the main product when 235/92 U undergoes beta decay? - Answer -235/93 Np
What type of radioactive decay produces a daughter nuclide that is the same element as the
parent nuclide? - Answer -gamma
What is the main product when 249/97 Bk emits a gamma ray? - Answer -249/97 Bk
Which type of particle can be emitted by an unstable nucleus?
A) 4/2 He
B) 0/+1 e
C) 0/-1 e
D) all of the above
E) none of the above - Answer -D) all of the above
A Geiger-Muller counter detects radioactivity by: - Answer -ionization of argon gas in a chamber
which produces an electrical signal.
3|Page
, A scintillation counter detects radioactivity by: - Answer -emission of light from a NaI crystal
when radioactivity passes through the crystal.
If the half-life of a radioactive isotope is 32 days, how many half-lives must pass before a 3.0
gramsample is less than 0.03 grams? - Answer -7
Tritium ( 3/1 H ) is an isotope of hydrogen that is sometimes used to make the hands of watches
glow in the dark. The half-life of tritium is 12.3 years. After 49 years, approximately how much
of the original tritium remains? - Answer -6.25%
If an object has 6.25% of the C-14 (t-1/2 = 5,720 years) activity as a living organism, the age of
the item is: - Answer -22,920 years.
If an object has 25% of the C-14 (t-1/2 = 5,720 years) activity as a living organism, the age of the
- Answer -11,460 years.
The first person to artificially cause a nucleus to undergo a fission reaction was: - Answer -Enrico
Fermi.
4|Page
