What is the difference between a light-year and an astronomical unit?

What is the molar mass of potassium nitrate, kno3

In 2002, the rare earth elements mine in mountain pass, california was closed because

In the following table, all the columns for the element calcium are filled out correctly. element electron structure of atom electron structure of ion net ionic charge calcium 1s22s22p63s23p64s2 1s32s22p63s23p64s1 +1 true false