Question

16 multiple choice 1 point calculate the amount of energy released by the nuclear reaction of 95 kilograms of uranium? 8.55x10^18 j 2.85x10^10 j 5.70x10^10 j 9.47x10^14 j 17 multiple choice 1 point how much mass is required to create a nuclear explosion that will release 5.40x10^18 joules of energy? 55 kg 60 kg 65 kg 70 kg 18 multiple choice 1 point the isotope lawrencium - 262 has a half - life of 4 hours. if a sample has an initial mass of 192.0 grams, then how much of the sample will remain after 20 hours. 2 4 6 8

Explanation:

Step1: Use Einstein's E=mc² for Q16

$E = 95\times(3\times10^{8})^{2}=8.55\times10^{18}\text{ J}$

Step2: Rearrange E=mc² for Q17

$m=\frac{5.40\times10^{18}}{(3\times10^{8})^{2}} = 60\text{ kg}$

Step3: Calculate half - life for Q18

Number of half - lives $n=\frac{20}{4}=5$. Remaining mass $m = 192\times(\frac{1}{2})^{5}=6$ grams.

Answer:

1. $8.55\times10^{18}\text{ J}$
2. 60 kg
3. 6