ANS:D - endothermic

An endothermic reaction is a chemical reaction that absorbs heat energy from its surroundings during the process. In other words, in an endothermic reaction, the products have a higher energy level than the reactants, and this energy difference is taken from the surrounding environment. Here's what happens during an endothermic reaction:

1. Energy Absorption: Energy is absorbed from the surroundings, usually in the form of heat, to break the bonds in the reactant molecules. This energy is used to overcome the activation energy barrier required to initiate the reaction.
2. Reactant Conversion: Once the reactant molecules have absorbed enough energy, they undergo chemical changes to form products. These products have higher potential energy than the reactants.
3. Surrounding Cooling: Since heat energy is absorbed from the surroundings, the temperature of the surroundings decreases during the reaction. This cooling effect is often noticeable in the environment surrounding the reaction vessel.

Examples of endothermic reactions include the melting of ice, evaporation of water, photosynthesis, and the decomposition of ammonium carbamate into urea, as in the production process of urea. These reactions are characterized by a decrease in temperature in the vicinity of the reaction or the absorption of heat by the reaction mixture. Overall, endothermic reactions play a crucial role in various natural and industrial processes, absorbing heat energy from their surroundings to drive chemical transformations.