Control rods are used in nuclear reactors to regulate the rates of uranium and plutonium nuclear fission. The control rods must be able to take in neutrons for this function without fissioning. To inhibit neutrons of varied energy, control rods are constructed from cross-sections. To regulate the pace of nuclear fission, control rods comprised of boron, cadmium, silver, and indium are used.
Hence, "Option B" is the right response.
We are aware that control rods regulate the fission rate of uranium or plutonium. Often, control rods are constructed of metals like silver, cadmium, boron, or indium. alloys or compounds like titanium diboride, zirconium diboride, and high boron steel. These substances can absorb several neutrons without undergoing nuclear fission. For neutrons of varying energy, these elements have a variety of neutron capture cross-sections.
To control the rate of the nuclear chain reaction, control rods are placed into the core of a nuclear reactor and adjusted. The amount and placement of control rods affect the reactor's reactivity, as does their distance from the reactor. To start the nuclear chain reaction, the control rods are partially withdrawn from the core.
We can use cadmium rods as control rods because they have the ability to absorb neutrons without fissioning themselves.
Therefore, option (B) is correct.
Match the LIST-I with LIST-II
LIST-I (Type of decay in Radioactivity) | LIST-II (Reason for stability) | ||
---|---|---|---|
A. | Alpha decay | III. | Nucleus is mostly heavier than Pb (Z=82) |
B. | Beta negative decay | IV. | Nucleus has too many neutrons relative to the number of protons |
C. | Gamma decay | I. | Nucleus has excess energy in an excited state |
D. | Positron Emission | II. | Nucleus has too many protons relative to the number of neutrons |
Choose the correct answer from the options given below:
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The density of the copper ($^{64}Cu$) nucleus is greater than that of the carbon ($^{12}C$) nucleus.
Reason (R): The nucleus of mass number A has a radius proportional to $A^{1/3}$.
In the light of the above statements, choose the most appropriate answer from the options given below:
Match the LIST-I with LIST-II
\[ \begin{array}{|l|l|} \hline \text{LIST-I} & \text{LIST-II} \\ \hline A. \ ^{236}_{92} U \rightarrow ^{94}_{38} Sr + ^{140}_{54} Xe + 2n & \text{I. Chemical Reaction} \\ \hline B. \ 2H_2 + O_2 \rightarrow 2H_2O & \text{II. Fusion with +ve Q value} \\ \hline C. \ ^3_1 H + ^2_1 H \rightarrow ^4_2 He + n & \text{III. Fission} \\ \hline D. \ ^1_1 H + ^3_1 H \rightarrow ^4_2 H + \gamma & \text{IV. Fusion with -ve Q value} \\ \hline \end{array} \]
Choose the correct answer from the options given below:
Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic physics, which studies the atom as a whole, including its electrons
‘R’ represents the radius of the nucleus. R = RoA1/3
Where,
The mass number (A), also known as the nucleon number, is the total number of neutrons and protons in a nucleus.
A = Z + N
Where, N is the neutron number, A is the mass number, Z is the proton number
Mass defect is the difference between the sum of masses of the nucleons (neutrons + protons) constituting a nucleus and the rest mass of the nucleus and is given as:
Δm = Zmp + (A - Z) mn - M
Where Z = atomic number, A = mass number, mp = mass of 1 proton, mn = mass of 1 neutron and M = mass of nucleus.