Answer:
1. B
2. D
Explanation:
1. Radioactive decay occurs when a radioactive particle cannot maintain a high energy state due to its own weight. When a radioactive element (eg. Uranium) undergoes radioactive decay, its product/s (following the previous example, Uranium decays into Thorium) are more stable than its reactants.
The question might remain that after Uranium decays to Thorium, where does the extra mass go? The extra mass is released as an alpha particle, and through this process, a lot of energy is released as gamma radiation.
Hence, the answer is:
During radioactive decay, atoms break down releasing particles or energy.
2. The half-life of an element is referred to as:
The length of time taken for one half of the radioactive atoms in a sample to decay.
Hence, since the question states the definition of a half-life, the answer is D.
