A . She gets promotion at work
It would be C. Burning coal contributes to warmer global temperatures
Answer:
C) X=100%; Y=0%
B) X=50%; Y=50%
Explanation:
The oldest rocks on Earth are about four billion years old. When a rock forms, it contains unstable isotope and no daughter isotopes, so every rock will contain 100% parent isotope and 0% daughter isotope.
The half-life of the radioactive isotope Of this particular rock is 5730 years. The half-life is an amount of time needed for half of the parent isotope (50%) to become a daughter isotope. In this case, after 5730 years, half of the initial parent isotope will transform to daughter isotope, which means that after 5730 years, there will be 50-50 of the parent and daughter istotopes presented in the rock. After two half-lives, there will be only 25% of the parent isotope remaining (that’s half of the previous 50% which remained after first half-life), and after three half-lives, there will be only 12,5% of the parent isotope remaining and so on.
Watermelon and rubber bands; shows weakness of how the watermelon has evolved over time?
