The half-life period for a radioactive substance is $15$ minutes. How many grams of this radioactive substance is decayed from $50$ gram of substance after one hour?

37.5

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25

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43.75

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46.875

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Solution

The correct option is D $46.875$
For n-half lives the mass of a reactant is ${(\frac{1}{2})}^{n}$ of the original.

1 hr = 60mins = $4 \times (15 m i n s) = 4 \times t_{\frac{1}{2}}$
$n = 4$

$∴$ the mass is ${(\frac{1}{2})}^{4} \times 50 g = 3.125 g$

$∴$ decayed mass $= 46.875$ g

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The half-life period for a radioactive substance is 15 minutes. How many grams of this radioactive substance is decayed from 50 gram of substance after one hour?

The correct option is D 46.875For n-half lives the mass of a reactant is (12)n of the original.1 hr = 60mins = 4×(15 mins)=4×t12n=4∴ the mass is (12)4×50g=3.125g∴ decayed mass =46.875g

The half-life period for a radioactive substance is $15$ minutes. How many grams of this radioactive substance is decayed from $50$ gram of substance after one hour?

The correct option is D $46.875$
For n-half lives the mass of a reactant is ${(\frac{1}{2})}^{n}$ of the original.

1 hr = 60mins = $4 \times (15 m i n s) = 4 \times t_{\frac{1}{2}}$
$n = 4$

$∴$ the mass is ${(\frac{1}{2})}^{4} \times 50 g = 3.125 g$

$∴$ decayed mass $= 46.875$ g