ANS:B - endothermic

Dehydration of ammonium carbamate to yield urea is an exothermic reaction. Explanation:

1. Exothermic Reaction: An exothermic reaction is a chemical reaction that releases energy in the form of heat to its surroundings. In the case of the dehydration of ammonium carbamate to produce urea, the reaction releases heat as a by-product.
2. Dehydration Reaction: The dehydration of ammonium carbamate involves the removal of water molecules from the ammonium carbamate molecule to form urea. This process typically occurs with the liberation of heat energy.
3. Energy Release: During an exothermic reaction, the reactants have higher potential energy than the products. As the reaction progresses, the potential energy of the system decreases, and the excess energy is released into the surroundings in the form of heat.
4. Significance: The exothermic nature of the dehydration reaction is important in industrial processes for urea production. It contributes to the overall energy balance of the process and may influence reactor design and operating conditions.
5. Autocatalytic or Catalytic Reactions: While certain reactions may be autocatalytic or catalytic, meaning they are accelerated by the presence of their own products or a catalyst, respectively, the dehydration of ammonium carbamate to urea is primarily characterized as exothermic due to the heat release during the reaction.