Show by equations, the effect on the proton number Z and mass number A of the parent nucleus brought about by the two types of radioactive decay. [5 MARKS]

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Solution

Each Explanation: 2.5 Marks

Radioactive decay takes place either by $α - e m i s s i o n o r β e m i s s i o n$ .

1. When a radioactive nucleus decays by emitting an alpha - particle, its mass number (A) decreases by 4 units while its proton number (Z) decreases by 2 units. The equation can be represented as :
$_{Z}^{A} X \to_{Z - 2}^{A - 4} Y +_{2}^{4} H e (α - p a r t i c l e)$

2. When a radioactive nucleus decays by emitting a $β - p a r t i c l e,$ there is no change in its mass number (A) but its proton number increases by one unit. The equation can be represented as :
$_{Z}^{A} X \to_{Z + 1}^{A} Y +_{- 1}^{0} β + E n e r g y$

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