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.
Answer:
2.6%
Explanation:
As, 1 ounce (oz) = 0.0625 pounds (lb)
Therefore, weight of baby at discharge = 7 lb,1 oz = 7+0.0625 lb = 7.0625 lb
Since, 1 oz = 0.0625 lb
⇒ 4 oz = 4×0.0625 = 0.25 lb
Therefore, weight of baby at birth = 7 lb,4 oz = 7+0.25 lb = 7.25 lb
The <u>amount of weight lost</u> is equal to the difference of weight of the baby at birth and discharge.
Therefore, <u>weight lost</u> = 7.25 lb - 7.0625 lb = <u>0.1875 lb</u>
Now, the <u>percentage of weight lost</u> by the baby is given by the amount of weight lost divided by the weight of the baby at birth.
Therefore, <u>the percentage of weight los</u>t = weight lost ÷ weight at birth = 0.1875 lb ÷ 7.25 lb × 100 = <u>2.6% </u>
Answer:
At birth, there are approximately 1 million eggs; and by the time of puberty, only about 300,000 remain. Of these, only 300 to 400 will be ovulated during a woman's reproductive lifetime. Fertility can drop as a woman ages due to decreasing number and quality of the remaining eggs.
Explanation:
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Right answer is B . Trust me .
Answer:
The correct answer is - Frequency is the number of wavelengths, which is measured in hertz.
Explanation:
Frequency is the number of waves that go through a fixed point at a particular time. Hertz is the SI unit for frequency which means that one hertz is equal to a unit number of waver passes in a unit time to a fixed point.
As the frequency of a wave increases which means the number of waves increases in the unit time, the shorter the wavelength will be.
a higher frequency wave has more energy than a lower frequency wave with the same amplitude.
