Department of Pre-University Education, Karnataka course PUC Karnataka Science Class 12
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# The Half-life of 226ra is 1602 Y. Calculate the Activity of 0.1 G of Racl2 in Which All the Radium is in the Form of 226ra. Taken Atomic Weight of Ra to Be 226 G Mol−1 - Physics

#### Question

The half-life of 226Ra is 1602 y. Calculate the activity of 0.1 g of RaCl2 in which all the radium is in the form of 226Ra. Taken atomic weight of Ra to be 226 g mol−1 and that of Cl to be 35.5 g mol−1.

#### Solution

Given:-

Half-life of radium, T1/2 = 1602 years
Atomic weight of radium = 226 g/mole
Atomic weight of chlorine = 35.5 g/mole

Now,

1 mole of RaCl2 = 226 + 71 = 297 g

297 g = 1 mole of RaCl2

0.1  "g" = 1/297 xx 0.1 mole of "RaCl"_2

Total number of atoms in 0.1 g of "RaCl"_2 , N

= (0.1 xx 6.023 xx 10^23)/297 = 0.02027 xx 10^22

∴ No of atoms, N = 0.02027 xx 10^22

Disintegration constant , lambda = 0.693/T_(1"/"2)

= 0.693/(1602 xx 365 xx 24 xx 3600)

= 1.371 xx 10^-11

Activity of radioactive sample , A = lambdaN

= 1.371 xx 10^-11 xx 2.027 xx 10^20

= 2.8 xx 10^9 disintegrations/second

Is there an error in this question or solution?

#### APPEARS IN

Solution The Half-life of 226ra is 1602 Y. Calculate the Activity of 0.1 G of Racl2 in Which All the Radium is in the Form of 226ra. Taken Atomic Weight of Ra to Be 226 G Mol−1 Concept: Radioactivity - Introduction of Radioactivity.
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