need help with 2,3, and 4 please!

3. There are two chiral centers in one of the constitutional isomers of CsH18 and four other isomers have one chiral center each. Clearly indicate which carbon(s) in at least 4 stereoisomers which qualify as chiral centers. Example: C\#3 in 2,2,3-trimethylpentane \[ \begin{array}{l} \text { \# _.... in } \\ \text { C\# _...._ in } \\ C \#_{\text {_..... in }} \\ C \#_{\text {_..... in }} \\ \end{array} \] 4. Classify each pair of molecules as constitutional (C), diastereomers (D), or enantiomers (E). a. b