DEFINITION:::::;;The type of reactions in which energy is releases to the environment are called Exothermic reactions.
EXAMPLE::: formation of carbon dioxide and urea formation are actually the examples of exothermic reaction..
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Answer: option d: The nucleus of Atom Q is more stable than the nucleus of Atom P.
Explanation:
Atom P is radioactive and disintegrates, it emits beta particles (high speed electrons or positrons) because it is not stable. On disintegration, it forms a stable Atom Q which is non-radioactive and thus it does not disintegrates further.
Thus, the correct option is only d. The nucleus of Atom Q is more stable than the nucleus of Atom P.