Select answers to the questions listed below from the following list of elements whose symbols start with the letter C: C, Ca, Cr, Co, Cd, Cl, Cs, Ce, Cm, Cu, and Cf. (You should expect to use some symbols more than once.) 

(a). Which are nonmetals? 

(b). Which are main group elements? 

(c). Which are lanthanides? 

(d). Which are transition elements? 

(e). Which are actinides? 

(f). Which are gases?