A radioactive isotope has a half-life of 3 hours. If a scientist has 30 grams of the isotope, how much is left after 15 hours

Which element is classified as an alkali metal?

Which of the following stages would come first in the life of a star? Neutron star White dwarf Protostar Black hole

What is the texture and appearance of oil

The effective nuclear charge for an atom is less than the actual nuclear charge due to A) shielding. B) penetration. C) paramagnetism. D) electron-pair repulsion. E) relativity

H + atomic mass number

Cracks in rocks chemical or mechanical

A large boulder falls from an underwater ledge and crashes on the floor of the ocean. A pod of dolphins is 800 meters away. Determine how long it takes for the sound of the crash to reach the dolphins. A) 0.5 sec B) 0.3 sec C) 2.3 sec D) 1.9 sec

Given 4.80g of ammonium carbonate, find: Number of moles of the compound Number of moles of ammonium ions Number of moles of carbonate ions Number of moles of hydrogen atoms Number of hydrogen atoms

The density of water is 1.0 g/cm3 will rubbing alcohol float with a density of 0.81 g/cm3

Write an equation that shows the formation of the phosphide ion from a neutral phosphorus atom.