Assertion : A reaction which is spontaneous and accompanied by...

$\Delta G=\Delta H-T \Delta S$ As the reaction is accompanied by decrease in randomness, $\Delta G=\Delta H+T \Delta S \quad[\because \Delta S$ is negative $]$ For reaction to be spontaneous $\Delta G$ should be negative which is possible only if reaction is highly exothermic i.e $\Delta H$ is negative. Exothermic reactions may be accompanied by increase or decrease of randomness.