The half life period of Pb210 is 22 years. If 2g of Pb210 is taken, then after 11 years the amount of Pb210 will be present is

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Q. The half life period of Pb210 is 22 years. If 2g of Pb210 is taken, then after 11 years the amount of Pb210 will be present is

(a) 0.1414g

(b) 1.414g

(c) 2.828g

(d) 0.707g

Click to See Answer :
Ans: (b)
Sol: N = N0(1/2)n , Where n = t/T1/2

N/N0 = (1/2)n

As , m ∝ N

m/m0 = (1/2)n

m/2 = (1/2)1/2 = 1/√2

m= 2/√2

m = √2 = 1.414

 

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