CBSE Class 10 Answered

Respiration is an exothermic process because if you feel the carbon dioxide exhaled on your palms it is slightly warm. Though the temperature is not that high but you can feel the warmth.

For decomposition also, heat is released and gases are evolved. That is why you get a bad smell from decomposed matter. Heat is alos released though not on a very large scale. For example in a bio gas plant, gases are released when decomposition of metatre takes place which is bio gas which is used as a fuel. The temperature of the dome is also high which shows that it is an exothermic process.

You can determine whether a reaction is exothermic or endothermic by measuring the differnce in temperature and finding whether heat is absorbed or evolved.