A lot of heat is produced in the reaction, which may even cause the water to boil. Hence it is a combination reaction as well as exothermic reaction.

The rxn in which heat is liberated is  called exothermic rxn  so, option C is correct

Exothermic reaction:
When Astha added quick lime to water and observed heat production, it indicates that an exothermic reaction has taken place. In an exothermic reaction, heat is released to the surroundings.

Explanation:
When quick lime (calcium oxide, CaO) is added to water (H2O), a chemical reaction occurs. The reaction can be represented by the following equation:

CaO + H2O → Ca(OH)2 + heat

The quick lime (CaO) reacts with water (H2O) to form calcium hydroxide (Ca(OH)2) and release heat. This heat is the result of the energy released during the formation of new chemical bonds between the calcium and hydroxide ions.

Reasons for heat production:
1. Formation of new chemical bonds: During the reaction, the calcium oxide and water molecules rearrange their atoms to form new chemical bonds in calcium hydroxide. This bond formation releases energy in the form of heat.

2. Exothermic nature of the reaction: The reaction between quick lime and water is known to be exothermic. This means that the overall energy of the reactants is higher than the energy of the products. As a result, excess energy is released in the form of heat.

Significance of heat production:
The production of heat in this reaction can have several important implications, including:

1. Utilization in various applications: The exothermic nature of this reaction can be harnessed for various purposes, such as in the production of heat for industrial processes or in chemical reactions that require high temperatures.

2. Safety precautions: The heat produced during the reaction can be significant, so it is important to handle the reaction carefully and take appropriate safety precautions to avoid any accidents or burns.

Conclusion:
Astha observed the production of heat when quick lime was added to water, indicating an exothermic reaction. The heat is released due to the formation of new chemical bonds in the resulting product, calcium hydroxide. Understanding the nature of this reaction can help in utilizing the heat produced for various applications and ensuring safety during the reaction.