I don't get Sibton's answer to 2. I have spent a lifetime campaigning against odd one out type of questions unless the answer is accompanied by the reason why. Banana seems the choice for 1 but for different reasons, each equally valid in my opinion (though I'm not sure about the oil bit)
If these are algebraic expressions you could argue that 10w is the odd one out as 4 is a factor of all the others. See what I mean about giving the reason why?