A sample of gaseous neon atoms at atmospheric pressure and 0°C contains 2.69×10^22 atoms per liter. The atomic radius of neon is 69 pm. Required:
a. What fraction of the space is occupied by the atoms themselves?
b. What does this reveal about the separation between atoms in the gaseous phase?

Americium-241 undergoes fission to produce three neutrons per fission event. if a neutron-absorbing material is mixed in with this sample so that the rate of neutron production drops down to 1.8 neutrons per fission event, which will be effective at achieving a critical mass? check all that apply. remove a deflective shield surrounding the sample. remove absorbent material mixed in with the sample. compress the sample of americium-241.

650.j is the same amount of energy as? 2720cal1550cal650.cal2.72cal

What is a substance? a. a physical property of matter b. a chemical property of matter c. an element or compound that cannot be physically separated d. characteristics used to tell the difference between mixtures