For a substance the average life for a-emission is 1620 years and for – McqOptions

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1.	For a substance the average life for a-emission is 1620 years and for b emission is 405 years. After how much time the 1/4 of the material remains after a and b emission [RPET 1999]
A.	1500 years
B.	300 years
C.	449 years
D.	810 years
Answer» D. 810 years

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