How do chemical changes differ from physical changes?

Chemical changes: A substance is chemically changed due to a chemical reaction, and forms a new substance and energy that is given off or absorbed. 
Examples: 
Paper burned
Souring milk
Baking a cake
Rusted iron
Physical change: Substance that doesn't change what the substance is.
Examples:
Paper cut in half
Water boiled 
Molded bread
Ice melted into a liquid
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Answer : option c) heat is released during the process.explanation :

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.

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