Hello There! ^_^
Your question: What is a darker contour line usually every fifth line..?
Your answer: An indes contour is a contour line that is usually in every fifth line.
Hope this helps!
Era is used to mark the boundaries of geological time scale by using radio carbon dating technique.
Explanation:
Geological time starts with Precambrian time.
Geologically, time is divided between the Precambrian era and present time into era.
The three eras are Paleozoic era, Triassic period and Cenozoic era.
Era is further divided into periods.
Scientists use radio carbon dating to study fossils and rock formation. With this study they were able to divide them in exact geological scale.
Geologic scale is the record of events in earth's history and evolution.
Answer:
Have different numbers of neutrons
Explanation:
Isotopes of an element have different atomic numbers because thy differ in neutron number even though proton number remains the same across the isotopes. The mass number is the summation of the proton and neutron number. Phosphorus has approximately 23 isotopes whose mass number range between 25 and 47. Only ³¹P is stable.
