<span>If I were attempting to date a rock sample that I suspect to be incredibly old, i would use radioactive isotopes with a long half life. When dating rocks and fossils to discover approximately how old they are, radioisotope dating is used on igneous rocks found near fossils. Things like Uranium 235, which is an unstable radioactive isotope of elements, decays at a constant rate over time so can be useful in determining age.</span>
Answer:
B)an amine group, a functional R group, and a carboxyl group
Explanation:
Answer:
Planet Y
Explanation:
Planet Y has the smaller period because it takes less time to orbit the star. This is because it has less distance to travel compared to X.
Answer:
Closed the first one
Explanation:
In amphibians, reptiles, birds, and mammals, blood flow is directed in two circuits: one through the lungs and back to the heart, which is called pulmonary circulation, and the other throughout the rest of the body and its organs including the brain (systemic circulation).
most mammals, have closed cardiovascular systems. The two main circulation pathways in invertebrates are the single and double circulation pathways.
Answer:
a
a process that selects variations to help with survi al and that spreads the variation to more offspring
Explanation:
the weak don't survive the strong thrive
