The central atom in the clf4 ion has nonbonded electron pair(s) and bonded electron pair(s) in its valence shell.

ClF4 is the chemical formula for tetrafluorochlorate. Chlorine has a valence electron of 7 in its valence shell. Each of the electron is to be paired with another electron from the second atom, fluorine. Since there are only 4 fluorine atoms, 4 of the atoms of chlorine will bond to 4 fluorine atoms. Then, we are left with only 3 atoms. Two atoms will be paired with each other. One is the unpaired.

The words that would complete the sentence is one (1) and two (2). 

It shows that the experiment is designed properly.