Give the meaning of a dh value of –400 kj in a reaction.

There are two ways in which the meaning of DH value of –400 kJ in a reaction can be explained. The first way is that the reaction gives out 400 kJ of energy via the process of heat release. The other way that it can be easily explained is that it is an exothermic reaction. I hope the answer has helped you.

I’m guessing you’re more alert to yourself or your surroundings if you’re more concentrated

Idont know. if you want an answer you need to give us some context dude.