Formaldehyde $($CH$2$O$)$ is produced industrially by the catalytic oxidation of methanol $($CH$3$OH$)$ according to the reaction:

$2$ CH$3$OH $+$ O$22$ CH$2$O $+2$H$2$O

However, some of the formaldehyde reacts with oxygen producing carbon monoxide and water:

$2$

CH$2$O $+$ O$22$ CO $+2$H$2$O

Methanol and $50\%$ excess air is supplied to the reactor. The fractional conversion of methanol is $0\mathrm{.}9$ and the fractional yield of formaldehyde is $0\mathrm{.}86.$ Calculate $($a$)\%$ composition of the product stream $($b$)$ the selectivity of formaldehyde production relative to carbon monoxide production