Question

Give reasons :

a) All decomposition reactions are endothermic reaction.

b) Respiration is exothermic reaction.

c) Magnesium ribbon should be rubbed before burning.​

Answer 1

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$\huge\tt{a)}$Decomposition reactions are usually endothermic because they involve breaking of bonds. Breaking bonds requires an input of energy, while forming bonds releases energy.

$\huge\tt{b)}$Respiration is considered as exothermic reaction because energy is released in this process. Glucose combines with oxygen present in our cells to form carbon dioxide and water along with energy.

$\huge\tt{c)}$Like rusting in case of iron, with magnesium, the oxide layer forms a white coating on the outside of the metal that will slow down or interfere with the burning process. Rubbing with sand paper helps to remove this oxide layer due to which burning speeds up

Answer 2

Answer:

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