Question

Give an example of each of the following chemical changes : An endothermic reaction.
A. making ice cubes
B. condensation of rain from water vapour
C. baking bread
D. mixing sodium sulfite and bleach

Answer 1

Hint: The endothermic reactions are reactions in which heat is provided or given in the reactant side of the reaction such that the reaction proceeds forward. On the other hand in exothermic reactions are reactions in which heat is released in the product side of the chemical reaction.

Complete step by step answer:
Now we know that heat is released in exothermic reactions and heat is provided in an endothermic reaction. So one by one we will analyse the options. Making ice cubes is an exothermic reaction because the molecule releases heat energy to the surroundings so that it can become cool and transform to ice. Condensation of rain from water vapour is an exothermic reaction because the water vapour has to release the heat energy to the surroundings so that it can transform itself to liquid phase. In the process of baking bread the ingredients like flour and yeast are heated before making the dough. So heat energy is given to the ingredients for baking bread. So it is an endothermic reaction. When we mix sulfite and bleach heat is released in the product side, so it is an exothermic reaction.
From the above explanation and discussion it is clear to us that baking bread is an endothermic reaction .

So the correct answer of the given question is : C. baking bread

Note:
Evaporation is an example of endothermic reaction because we have to provide energy to the liquid to change it to a gaseous state. Photosynthesis process is also an example of endothermic reaction .Respiration is an example of exothermic reaction , because energy is released in the process of respiration .