iGCSE Physics (0625) 5.2.3 Radioactive decay-Exam Style Questions- New Syllabus
▶️ Answer/Explanation
Detailed solution:
Beta decay occurs in an unstable nucleus when there is an excess of neutrons.
During this process, a neutron transforms into a proton and an electron (the beta-particle).
The nuclear equation for this change is represented as: n→p+e − .
The newly formed proton remains in the nucleus, increasing the atomic number by 1.
The electron is ejected from the nucleus at high speed as a β-particle.
Options A and B are incorrect because β-particles originate from the nucleus, not electron shells.
Option D describes the process of positron emission, which is not the standard β − decay discussed here.
▶️ Answer/Explanation
Detailed solution:
Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation.
A key characteristic of all nuclear decay, including $\alpha$-decay and $\beta$-decay, is that it is spontaneous.
This means the decay occurs without any external trigger and cannot be affected by physical conditions like temperature or pressure.
Furthermore, the process is random, meaning it is impossible to predict exactly which nucleus in a sample will decay at any given moment.
Since these fundamental properties apply to all types of nuclear emissions, both alpha and beta processes share these traits.
Therefore, Statement B is the only accurate description of how these emissions occur.
▶️ Answer/Explanation
Detailed solution:
Beta decay (β − ) occurs when a nucleus has an excess of neutrons, making it unstable.
During this process, a neutron in the nucleus transforms into a proton and an electron.
The newly formed proton remains within the nucleus, increasing the atomic number by 1.
The electron, known as the beta-particle, is ejected from the nucleus at high speed.
This nuclear transformation is represented by the equation: n→p+e − .
Consequently, Option B accurately describes the fundamental change occurring inside the nucleus.