please answer
explain the reason behind the test tube becoming hot, just after carrying out the nuetralization reaction

The test tube becomes hot just after carrying out the neutralization reaction because the reaction involves mixing of an acid with a base or a base with an acid. In this process the test you becomes her due to the reaction of heat involved in it. The heat reaction involved in it is called exothermic reaction or endothermic reaction. Exothermic reaction happens when the solution is producing the heat and endothermic reaction happens when the solution is taking the heat from the surface. All the neutralization reaction involves the heat, it could may be endothermic reaction or exothermic reaction depending upon the type of solution.