Explanation:
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The scientific evidence that scientists use in supporting or critiquing the conclusions of experiments usually consists observations based on large sample sizes.
Answer:
Explanation:
percentage abundance of third isotope = 100 - ( 78.900 + 10.009)
= 11.091 %
Atomic mass
24.1687 x .789 + 25.4830 x .10009 + 24.305 x .11091
19.069 + 2.5506 + 2.69566
= 24.3153 amu
Half-life of a radioactive substance is the time required to reduce the amount of substance to half of its initial amount.
In present case, half-life is material is given as 1000 years and initial amount of material is given as 400 kg
Answer 1) Since, half-life of radio-active substance is 1000 years, therefore after 1st half life, amount of the material will be left to half the initial amount. Hence, amount of substance left after 1000 years = 400/2 = 200 kg.
Answer 2) For 2000 years, radioactive material has crossed 2 times the half life. Therefore , amount of the material will be left to 1/4 the initial amount. Hence, amount of substance left after 2000 years = 400/4 = 100 kg.
Answer 3) For 4000 years, radioactive material has crossed 4 times the half life. Therefore , amount of the material will be left to 1/16 the initial amount. Hence, amount of substance left after 4000 years = 400/16 = 25 kg.
