Consider the following spontaneous reaction
 $$\begin{gathered} 2{\mathrm{C}}_8{\mathrm{H}}_{18}\left(\mathrm{g}\right)+25{\mathrm{O}}_2\left(\mathrm{g}\right)\to 16{\mathrm{CO}}_2\left(\mathrm{g}\right)+18{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right) \\ \text{ The sign of }\mathrm{\Delta H},\mathrm{\Delta S},\mathrm{\Delta G}\text{ would be respectively } \end{gathered}$$

$2{\mathrm{C}}_8{\mathrm{H}}_{18\left(\mathrm{g}\right)}+25{\mathrm{O}}_{2\left(\mathrm{g}\right)}⟶16{\mathrm{CO}}_{2\left(\mathrm{g}\right)}+18{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{g}\right)}$
The given reaction is a combustion reaction. Hence 
this will be an exothermic reaction.
$$\begin{gathered} \text{ i.e. }\mathrm{\Delta H}=-\mathrm{ve} \\ \text{ Further }\mathrm{\Delta n}=(18+16)-(2+25)=+\text{ ve i.e. }\mathrm{\Delta S}=+\text{ ve } \\ \mathrm{\Delta G}=\mathrm{\Delta H}-\mathrm{T\Delta S}=-\mathrm{\Delta H}-\mathrm{T\Delta S}=-\mathrm{ve} \end{gathered}$$