A radioactive element gets spilled over the floor of a room. Its half-life period is 30 days. If the initial activity is ten times the permissible value, after how many days will it be safe to enter t

Question

A radioactive element gets spilled over the floor of a room. Its half-life period is 30 days. If the initial activity is ten times the permissible value, after how many days will it be safe to enter the room?

TestHub · Accepted Answer

Activity ( − dt dN ​ ) ∝ N N = N ∘ ​ ( 2 1 ​ ) n N ∘ ​ N ​ = ( 2 1 ​ ) n 10 1 ​ = ( 2 1 ​ ) n ⇒ 10 = 2 n lo g 10 = nlog 2 ⇒ n = 0.301 1 ​ = 3.32 t = n × t 112 ​ = 3.32 × 30 = 99.6 days Hence, (D) is correct.

Chemistry - Chemical Kinetics Question with Solution | TestHub

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