Thus by 1803 there were two known rare earth elements, yttrium and cerium, although it took another 30 years for researchers to determine that other elements were contained in the two ores ceria and yttria (the similarity of the rare earth metals' chemical properties made their separation difficult).
For instance, students who pursue a Ph.D. in psychology usually take from five to seven years depending upon required coursework as well as internship and supervised residency requirements.
How long does it take to earn a bachelor's degree in psychology?   Four Years   Four (4) years of study are generally required for most Bachelor's degrees. Of course, there are the usual exceptions that test that rule by requiringâ¦ only three (3) years or as many as five (5) years.