He device that uses electrodes placed on the outside of the skull to record electrical activity within the brain, and is used in psychophysiological research, is called a(n)

The device that is being described above is the EEG or also known as the electroencephalogram. This is a type of test that is being used in the brain that will help in monitoring electrical activity. This device will enable to show the results of which are wavy lines that are being recorded. It is done by the communication with the impulses on the brain.

i'd say that the moon rock is about 2.2 billion years old.