iGCSE Physics (0625) 5.1.2 Nucleus-Exam Style Questions- New Syllabus
▶️ Answer/Explanation
Detailed solution:
Stable stars, such as the Sun, are primarily composed of hydrogen and helium. The energy source for these stars is nuclear fusion, a process where light nuclei join to form a heavier nucleus. In the core of a stable star, high temperatures and pressures allow hydrogen nuclei to fuse together. This reaction specifically converts hydrogen into helium and releases a vast amount of energy in the form of electromagnetic radiation. Unlike fission, which involves splitting heavy nuclei, fusion powers the lifecycle of stars during their stable main-sequence phase.
▶️ Answer/Explanation
Detailed solution:
In any nuclear reaction, the total nucleon number ($A$) and the total proton number ($Z$) must be conserved.
For the reactant side: total $A = 1 + 14 = 15$, and total $Z = 0 + 7 = 7$.
For the product side, the carbon isotope has $A = 14$ and $Z = 6$.
Let $x$ be represented as $\text{ }^{A}_{Z}x$. To balance the equation: $15 = 14 + A$ and $7 = 6 + Z$.
This gives $A = 1$ and $Z = 1$. The particle with a mass of $1$ and a charge of $+1$ is a hydrogen nucleus or a proton.
Thus, $x$ is a proton, which matches Option D.
▶️ Answer/Explanation
Detailed solution:
The nucleon number (A), also known as the mass number, represents the total number of protons and neutrons in the nucleus.
The number of protons is given as 5, which is also the atomic number (Z).
The relationship between these quantities is given by the formula: A=Z+N, where N is the number of neutrons.
By rearranging the equation to solve for neutrons, we get N=A−Z.
Substituting the given values: N=11−5=6.
Therefore, there are 6 neutrons in this atom of boron, making option B the correct choice.