The balanced equation for decane combustion is:
[tex]2C_{10}H_{22(l)}+31O_{2(g)}\to20CO_{2(g)}+22H_2O_{(g)}[/tex]
That is the balanced equation.
To calculate the volume of carbon dioxide, use the mass of decane and convert it to moles (use the molecular weight of decane, 142g/mol), then use the ration of the coefficients of carbon dioxide to decane to find the number of moles of CO2 produced:
[tex]0.400\operatorname{kg}\cdot\frac{1000g}{\operatorname{kg}}\cdot\frac{1mol}{142g}=2.82mol[/tex]
