If a radiographic substance's half-life is 20 years, how much of a 40 gram sample will be left after 60 years?

A. 5 grams

B. 10 grams

C. 20 grams

D. 30 grams

7 1/2 9 what does it equal I am having a little bit of trouble

Jane is an astronomer who has been observing objects that orbit the Sun in the asteroid belt. He finds a previously undiscovered round, rocky object that is not similar in shape to the rest of the asteroids. What has Abdid most likely found? a.

How does the carbon cycle work in the desert

Earthshine is illumination seen during which phase of the moon?

Which of the following is TRUE of independent agencies? a. They are created by Congress b. They are independent of both the President and the Executive Branch c. They are located only in the Cabinet Department d.

An atom of element A has 50 protons, what would the elements atomic number be?

Name 2 bodies of water associated with Germany

6. Which is a farming technique that could improve the soil and the environment? A using fueled machines that will turn the soil continuously B creating undisturbed layers of mulch in the soil C placing inorganic chemical fertilizers in the soil D

Which is an example of kinetic energy? A) a ball rolling across the floor B) the energy stored in gasoline C) a stretched spring D) a book sitting at the top of a bookshelf

Read the passage below and answer the question that follows. William has been living in a highly populated region in Eastern Europe for five years.