ANS:A - exothermic

An exothermic reaction is a chemical reaction that releases energy in the form of heat to its surroundings. In an exothermic reaction, the total energy of the products is lower than the total energy of the reactants. This energy difference is released as heat during the reaction. Here's what happens during an exothermic reaction:

1. Energy Release: Energy is released as the reaction progresses. This energy is typically in the form of heat, but it can also be in the form of light or sound, depending on the specific reaction.
2. Temperature Increase: Since heat is released, the temperature of the surroundings tends to increase during an exothermic reaction. This increase in temperature is often noticeable and can sometimes be significant, especially in highly exothermic reactions.
3. Enthalpy Change: In terms of thermodynamics, exothermic reactions have a negative enthalpy change (Δ𝐻<0ΔH<0), indicating that the overall change in heat content of the system is negative. This means that the system loses heat to the surroundings during the reaction.

Examples of exothermic reactions include combustion reactions (such as burning wood or gasoline), neutralization reactions (such as the reaction between an acid and a base to form water and a salt), and many types of chemical reactions used in industry and everyday life. In the context of the ammonia synthesis reaction, which is the reaction that produces ammonia (𝑁𝐻3NH3​), the process is exothermic. Heat is released as the reaction proceeds, contributing to the overall energy balance of the system.