Chemistry igcse hell please answer scientifically?

What products are formed when butane burns in excess air ?
-how to write a balanced equation
-how do you know what kind of end product you'll get
* need all in DETAIL please it's IGCSE thanks a lot !

Name the poisonous gas formed when butane undergoes incomplete combustion.

Excess air usually means complete combustion therefore that means you will most likely not have Carbon monoxide as an end product, just CO2 and H2O.

The poisonous gas that is produced during incomplete combustion, is Carbon Monoxide. Colourless and smell-less.

its C4H10 + 5O2 = 5H2O + 2CO2 + CO + C

Carbon dixide and water

C4H10 + 5O2 --> 4CO2 + Does not balance

C4H10 + 8O2 --> 4CO2 + Does not balance

2C4H10 + 13O2 --> 8CO2 + 10H2O

You know by doing your homework. That's what you take classes for.