The question asks to identify the type of reaction where heat is evolved. This relates to the energy changes that occur during chemical reactions. Reactions can either release energy (typically as heat) or absorb energy.
B) Exothermic reaction: An exothermic reaction is defined as a reaction that releases energy, usually in the form of heat, to its surroundings. When heat is "evolved," it means it is given off or released, which perfectly matches the definition of an exothermic reaction.
The question asks to identify the type of reaction where heat is absorbed from the surroundings. This directly relates to the energy change associated with a chemical reaction, specifically whether it releases or consumes heat.
Correct Option: C) Endothermic reaction is the correct answer because it describes a reaction where heat is absorbed from the surroundings.
This question asks about the sign of the enthalpy change (\(\Delta H\)) for an exothermic reaction. Understanding the definition of exothermic and endothermic reactions is key to answering this question.
Thus, for an exothermic reaction, the value of \(\Delta H\) is negative.
Correct Option: B) Negative
The question asks about the sign of the enthalpy change (\(\Delta H\)) for an endothermic reaction. We need to recall the definition of an endothermic reaction and how it relates to energy absorption and enthalpy change.
Correct Option: C) Positive
For an endothermic reaction, the system absorbs heat from the surroundings. This means the energy content of the products is higher than that of the reactants. Consequently, the change in enthalpy (\(\Delta H\)), which is defined as \(H_{\text{products}} - H_{\text{reactants}}\), will be positive.
The question asks to identify an exothermic reaction from the given options. An exothermic reaction is a chemical reaction that releases energy, usually in the form of heat or light, to its surroundings. This means the products have lower energy than the reactants.
Correct Option: C) Combustion of methane is an exothermic reaction because it releases a significant amount of heat and light energy.
The question asks to identify an endothermic process from the given options. An endothermic process is one that absorbs heat from its surroundings, causing the surroundings to cool down. Conversely, an exothermic process releases heat into the surroundings.
Correct Option: C) Melting of ice is an endothermic process because it requires the absorption of heat energy from the surroundings to change from a solid state (ice) to a liquid state (water).