Q25 of 94 Page 442

The half-life of 226Ra is 1602 y. Calculate the activity of 0.1g 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.

Molecular weight of RaCl2


So, 297 g of RaCl2 contains 6.023×1023 atoms


0.1 g contains



Now for decay constant(λ)



Activity = λA


where


A= no. of atoms


λ = decay constant




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