Question

the gases hydrogen and chlorine do not react with each other even if kept together for a long time in the presence of Sunlight the readily combine what does actually happened​

Answer 1

The reaction, in order to proceed, requires a catalyst.

• Why a catalyst is needed??

➡️ Reactants need to fulfill a necessity of having adequate activation energy in order for them to get converted into products. Since some of the Reactants don't have it or sometimes have less than what's required, the reactions however don't proceed.

So, when a catalyst is added, they lower the activation energy and allow the reaction to be proceeded. Also, HERE THE CATALYST IS SUNLIGHT.