When molecules collide, there is generally a delay before an explosion occurs, if an explosion occurs at all. This is because an explosion requires a chemical reaction to take place, which involves the breaking of chemical bonds and the formation of new bonds. These reactions require a certain amount of energy, which is called the activation energy.
The collision of molecules can provide energy to the system, but it is not always enough to overcome the activation energy needed for a chemical reaction to occur. If the energy of the collision is less than the activation energy, no reaction will occur and there will be no explosion. If the energy of the collision is equal to or greater than the activation energy, a chemical reaction may occur and an explosion may result.
The time delay between the collision of molecules and an explosion occurring depends on the nature of the molecules and the conditions under which the collision occurs. Some chemical reactions are very fast and can occur almost instantly, while others may take longer to reach the activation energy and proceed to completion.
It's worth noting that not all collisions between molecules result in an explosion. In many cases, the collision may simply transfer energy from one molecule to another without leading to a chemical reaction.