The instrument that is commonly used to measure the intensity of radioactivity is called a photographic plate magnet wilson cloud chamber geiger counter

The instrument is a Geiger counter and is used to measure radioactive level around people's bodies.

There is one s orbital, and there are three p orbitals, five d orbitals, and seven f orbitals. thus, the answer is b. do not confuse the number of orbitals in a subshell with the number of electrons the subshell can hold. each orbital can hold two electrons, so the capacity of an nf subshell is 14 electrons.