An internal combustion engine uses butane $(C_4{H}_{10})$ as a fuel. The molecular weights of air and butane are $29$ and $58\frac{g}{m}ol,$ respectively. It is required to:

Write the balanced chemical equation for butane with stoichiometric oxygen. $(2$ marks$)$

Write the balanced chemical equation for butane with $5\%$ excess air. $(2$ marks$)$

Obtain the stoichiometric air$/$fuel ratio. $(2$ marks$)$

Obtain the actual air$/$fuel ratio. $(2$ marks$)$

Calculate the fuel$-$equivalence ratio. $(2$ marks$)$

Determine if the fuel mixture is rich or lean. $(1$ mark$)$