Answer:
8 electrons
Explanation:
Number of atoms = 128
Half life = 15 s
After each half life, the number of atoms reduces by half. So we need to determine how many half lives are in 60s.
Number of half lives = 60s / 15s = 4
After the first life;
Number of electrons left = 128 / 2 = 64
After the second life;
Number of electrons left = 64 / 2 = 32
After the third half life;
Number of electrons left = 32 / 2 = 16
After the fourth half life;
Number of electrons left = 16 / 2 = 8
Answer:
C. 8
Explanation:
correct on gizmo; After one half-life (15 seconds), about 64 radioactive atoms will remain, half of the original 128. After a second half-life passes (30 seconds total), about 32 radioactive atoms will remain, half of 64. After a third half-life passes (45 seconds), about 16 radioactive atoms will remain. A time of 60 seconds represents four half-lives, so about 8 radioactive atoms will remain.
