1) There are only single bonds between the carbon atoms, so the ending is 'ane'. Thus, the answer is 2-methylbutane.
2) There is one triple bond between one pair of carbon atoms, so the ending is 'yne'. So, the answer is 2-butyne.
3) There is one double bond between one pair of carbon atoms, so the ending is 'ene'. So, the answer is 2-butene.
