Question 405: Atoms & Nuclei

Question

A radioactive substance decays to $${\left( {{1 \over {16}}} \right)^{th}}$$ of its initial activity in 80 days. The half life of the radioactive substance expressed in days is ____________.

Accepted Answer

$${N_0}\buildrel {{{{t_1}} \over 2}} \over
 \longrightarrow {{{N_0}} \over 2}\buildrel {{{{t_1}} \over 2}} \over
 \longrightarrow {{{N_0}} \over 4}\buildrel {{{{t_1}} \over 2}} \over
 \longrightarrow {{{N_0}} \over 8}\buildrel {{{{t_1}} \over 2}} \over
 \longrightarrow {{{N_0}} \over {16}}$$
$$4 	imes {t_{1/2}} = 80$$
$${t_{1/2}} = 20$$ days

Atoms & Nuclei

A radioactive substance decays to ${\left( {{1 \over {16}}} \right)^{th}}$ of its initial activity in 80 days. The half life of the radioactive substance expressed in days is ____________.

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