Calculate the decay constant of a radioactive isotope of half-life 138.5 s.

a

5.0 × 10\(^{-3}\) s\(^{-1}\)

b

5.1 × 10\(^{-3}\) s\(^{-1}\)

c

4.9 × 10\(^{-3}\) s\(^{-1}\)

d

5.2 × 10\(^{-3}\) s\(^{-1}\)

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a

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PerfectEmerole
4 months ago

t¹/² = 0.693/decay constant
therefore: ( cross multiply to make decay constant the subject of the formula)
Decay constant = 0.693/ t¹/²
DC = 0.693/ 138.5 = 0.0050s-¹
converting to standard form = 5×10-³s-¹ option A.

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