Question

30. If a radioisotope has a half-life of 2.0 hours, how long would it take for 93.7% of decompose? A 16 hours B. 14 hours C. 12 hours D. 10 hours E. 8 hours Equal

Answer 1

t1/2 = 2 hr

K   = 0.693/t1/2

      = 0.693/2   = 0.3465hr^-1

K   = 2.303/t log(a/(a-x)

0.3465 = 2.303/t log(100/100-93.7)

t   = 2.303/0.3465log(100/100-93.7)

    = 6.646log(100/6.3)

      = 6.646*1.2

      = 8 hours

E. 8 hours

4.1s^1

for s -orbital ml = 0

for clock wise direction spin quantum number is +1/2

2s^1

n = 2

l = 0

ml = 0

ms = +1/2

ml = 0

ms = +1/2