At the end of the third half-life, 5.25 grams of a radioactive material remains. What was the total amount of radioactive material at the start? 42
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Astudent observes a star from two positions of earth in its orbit, in summer and winter, and measures the change in the position of the star. which of these can be best calculated by this method?

25. what does meiosis create? haploids or diploid? somatic cells or gametes?

Imagine a rocket launching from earth and travelling to the moon. in which order would the rocket pass through the layers of the atmosphere? thermosphere, mesosphere, stratosphere, troposphere troposphere, mesosphere, stratosphere, troposphere thermosphere, stratosphere, mesosphere, troposphere troposphere, stratosphere, mesosphere, thermosphere