Which of the following cannot be the chemical symbol for an element
a. co
b. cf
c. b
d. cu

Cf is not a symbol

co = cobalt
b = barium
cu = copper

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.