If N0 is the original mass of the substance of half-life period t1/2 = 5 years, then the amount of substance left after 15 years is

Question

If N0 is the original mass of the substance of half-life period t1/2 = 5 years, then the amount of substance left after 15 years is (A) N 0 / 8 (B) N 0 / 16 (C) N 0 / 2 (D) N 0 / 4

Tardigrade Admin · Accepted Answer

After every half-life, the mass of the substance reduces to half its initial value.

N_{0} 5 years \frac{N _{0}}{2} 5 years \frac{N _{0} /2}{2}

= \frac{N _{0}}{4} 5 years \frac{N _{0} /4}{2} = \frac{N _{0}}{8}

Q. If $N_{0}$ is the original mass of the substance of half-life period $t_{1/2} = 5$ years, then the amount of substance left after $15$ years is

$N_{0} /8$

$N_{0} /16$

$N_{0} /2$

$N_{0} /4$

After every half-life, the mass of the substance reduces to half its initial value.
$N_{0} 5 years \frac{N _{0}}{2} 5 years \frac{N _{0} /2}{2}$
$= \frac{N _{0}}{4} 5 years \frac{N _{0} /4}{2} = \frac{N _{0}}{8}$

Q. If N0​ is the original mass of the substance of half-life period t1/2​=5 years, then the amount of substance left after 15 years is

N0​/8

N0​/16

N0​/2

N0​/4