Multiple choice questions in nuclear chemistry.

1. Magnesium-28 decays via beta emission, which equation represents the balanced nuclear equation?

 A.12Mg28 à -1e0 + 14Si28

 B.2Mg28 à 2He4 + 10Ne28

 C.12Mg28 à 1n0 + 13Al28

 D.12Mg28 à -1e0 + 13Al28

 E.none of the above

2. Complete the nuclear equation by 86Rn220 à 2He4 + ______ writing the symbol of the missing particle:

 A.84Po216

 B.84Po214

 C.82Pb218

 D.82Pb222

 E.none of the above

3. Silicon-26 decays via positron emission, which equation represents the balanced nuclear equation?

 A.14Si26 à -1e0 + 13Al26

 B.14Si26 à 2He4 + 13Al26

 C.14Si26 à 1e0 + 13Al28

 D.14Si26 à 1e0 + 13Al26

 E.none of the above

4. Complete the nuclear equation 10Ne19 à 1e0 + ______ by writing the symbol of the missing particle:

 A.9F18

 B.10Ne18

 C.9F19

 D.10Ne19

 E.none of the above

5. Argon-37 decays via electron capture emission, which equation represents the balanced nuclear equation?

 A.18Ar37 à -1e0 + 17Cl37

 B.18Ar37 + -1e0 à 17Cl37

 C.18Ar37 + 1e0 à 17Cl37

 D.18Ar37 + -1e0 à 16S37

 E.none of the above

6. 131I decays with a t1/2 = 8.07 hrs. If we begin with 3.0 mg, how much remains after 6 half-lives?

 A.0.0469 mg

 B.0.0234 mg

 C.0.50 mg

 D.0.25 mg

 E.0.01875

7. The half-life of Pa-234 is 6.75 hr.  Approximately what fraction of a sample of isotope remains after

20.25 hours?

 A.¼

 B.1/8

 C.1/16

 D.1/3

 E.½

8. The half-life of Rn-222 is 3.823 day. What was the original mass of a sample of this isotope if 0.0500 g

remains after 7.646 day?

 A.0.398 g

 B.0.199 g

 C.0.085 g

 D.0.800 g

 E.0.042 g

9. The half-life of Th-227 is 18.2 day. How many days are required for 0.70 of a given sample to decay?

 A.4 days

 B.16 days

 C.32 days

 D.64 days

 E.128 days

10. An object taken from a cave has a carbon-14 fraction which is 0.89 of the amount in a living organism.

How old is the object? (half-life for C-14 is 5730 yr)

 A.240 yrs

 B.480 yrs

 C.960 yrs

 D.1920 years

 E.3840 years