In the molecule CH3-CH2-C≡CH, the hybridization of the carbon atoms are: sp3 for the first carbon (CH3), sp3 for the second carbon (CH2), sp for the third carbon (C≡C), and sp for the fourth carbon (C≡CH). 

• sp3 hybridization: The first and second carbon atoms are each bonded to four other atoms (three hydrogen atoms and one carbon atom), so they are sp3 hybridized. 

• sp hybridization: The third and fourth carbon atoms are involved in a triple bond, which requires the use of sp hybrid orbitals to form the strong sigma bond and two pi bonds. 

Key points to remember:

• A carbon atom with single bonds to four other atoms is sp3 hybridized. 
• A carbon atom with one double bond and two single bonds is sp2 hybridized. 
• A carbon atom with a triple bond and one single bond is sp hybridized.