C5H12 has a symmetrical structure with one quaternary carbon. Its IUPAC name is:
2,2-Dimethylpropane
C5H12 is of the form CnH2n+2.
Hence it is a saturated alkane. Further, it is given that it has a quaternary carbon. Hence its structure is:
Longest chain = 3 carbons ⇒ word root = prop
Primary suffix = ane
Secondary prefix = 2,2-Dimethyl
IUPAC name is (c) 2,2-Dimethyl propane