What is the difference between an atom in the ground state and an atom in an excited state?
a. the atom in the ground state has less energy and is less stable than the atom in an excited state.
b. the atom in an excited state has one fewer electron than the atom in the ground state.
c. the atom in an excited state has more energy and is less stable than the atom in the ground state.
d. the atom in an excited state has one more electron than the atom in the ground state.

Asample of radium-226 will decay 1/4 of its original amount after 3200years. what is the half-life of radium-226?

Astudent is given a sample of a blue copper sulfate hydrate. he weighs the sample in a dry covered porcelain crucible and got a mass of 23.875 g for the crucible, lid, and sample. the mass of the empty crucible and lid was found earlier to be 22.652 g. he then heats the crucible to expel the water of hydration, keeping the crucible at red heat for 10 minutes with the lid slightly ajar. on colling, he finds the mass of crucible, lid, and contents to be 23.403 g. the sample was changed in the process to very light clue anhydrous cuso4. if there are again 100.0 g of hydrate, how many grams of cuso4 are in it? how many moles of cuso4? (hint: molar mass of cuso4 = 159.6 g / mole. what per cent of the hydrate is cuso4? you may convert the mass of cuso4 to moles.)

Why doesn't heat added to water make the tempature rise above 100c