Answer:9. The reactions in which heat is evolved (given out) are known as exothermic reactions. For example: The reaction between carbon and oxygen to form carbon dioxide:

C (s) + O2 (g) -> CO2 (g) + Heat

The reactions in which heat is absorbed are called endothermic reactions. For example: The reaction between nitrogen and oxygen to form nitrogen monoxide: N2 (g) + O2 (g) + Heat -> 2NO (g)

10. Respiration is considered an exothermic process becoz in respiration, energy (in the form of heat) is produced.

11. In Combination reactions, two or more substances combine to form a single substance. For example:

2Mg(s) + O2 (g) -> 2MgO(s)

While in decomposition reactions, single substance splits up into two or more simpler substances. For example:

CaCO3 (s) -> CaO (s) + CO2 (g)

Hence, decomposition reactions are called the opposite of combination reactions.. HOPE IT HELPS

Answer:

Explanation:

9076797681