Fill in the blanks with appropriate items : A radioactive substance decays 20% in 10 min if at start there are ` 5 xx 10^(20)` atoms present , after ________ hour the number of atoms will be reduced to ` 10^(18)`.

Fill in the blanks with appropriate items : A radioactive substance de

1.	Fill in the blanks with appropriate items : A radioactive substance decays 20% in 10 min if at start there are ` 5 xx 10^(20)` atoms present , after ________ hour the number of atoms will be reduced to ` 10^(18)`.
Answer» Correct Answer - `4.65` `k=(1)/(10) ln .(100)/(80) =(1)/(t) "in" (5xx10^(20))/(10^(18)) rArr (1)/(10)"in"(5)/(4)=(1)/(t) "in" 500 rArr (10 xx"in" 500)/("ln"(5)/(4))` `t=278.5` min. `t=4.641` hr.

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Fill in the blanks with appropriate items : A radioactive substance decays 20% in 10 min if at start there are ` 5 xx 10^(20)` atoms present , after ________ hour the number of atoms will be reduced to ` 10^(18)`.

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