When a hydrocarbon A undergoes complete combustion it requires 11...

By using the formula of combustion analysis:

${C}_{x}{H}_{y} + \left(x + \dfrac{y}{4}\right){O}_{2} \to {CO}_{2} + \dfrac{y}{2}{H}_{2}O$

Given, \left(x + \dfrac{y}{4}\right)a = 11a$</p><p>$x + \dfrac{y}{4} = 11$</p><p>\left(\dfrac{y}{2}\right)a = 4a$

$y = 8$,

then $x + \dfrac{8}{4} = 11$

$x = 11 - \dfrac{8}{4}$

$x = 9$

Formula $= {C}_{9}{H}_{8}$