How much oxygen is required to completely react with 10 g of C4H10?

Answer 1

You need to:

Write a balanced equation of the reaction of O2 with butane

C4H10 + O2 -> CO2 + H2O

Then work how how many moles of C4H10 the 10 g represents.

The work out how many moles of O2 needed

convert the moles of O2 to mass of O2. This assumes that mass is what is meant by 'how much' which could also mean volume, number of molecules and so on.