All questions of Nuclei for JEE Exam

Isobars are atoms of different elements with the same mass number but different atomic numbers.

• Isotones are atomic nuclei with the same number of neutrons (N) and different number of protons(Z)

Correct b is answer

Cadium rod is used to control the fission rate of uranium

Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways.

More than 99.99% of the mass of any atom is concentrated in its nucleus. If the mass of protons and neutrons (which are in the nucleus of every atom) is approximately one (1) atomic mass unit, then the relative mass of an electron is 0.0005 atomic mass units.

Around 200 MeV energy is released per fission. The exact value however depends on the fission products. Around 200 fission products have been identified. For calculation, exact equation(fission reaction) is required.

Fission result in the production of typically 2 or 3 neutron so on the average about 2.5 neutron released per unit. so correct answer is option a
for option c one uranium atom split into one barium and one krypton atom releasing 3 neutron.
but in this question average is asking so according to me and books 2.5 is correct

Binding energy per nucleon in the mass number range A = 30 to 170

The binding energy per nucleon is the energy required to separate a nucleus into its constituent nucleons. It is a measure of the stability of the nucleus, and it depends on the mass number of the nucleus. In the mass number range A = 30 to 170, the binding energy per nucleon is nearly constant. This means that the stability of the nucleus is nearly constant in this range.

Explanation:

The binding energy per nucleon is given by the formula:

BE/A = (ZmH + NmN - M)/A

where BE is the binding energy, Z is the atomic number, N is the number of neutrons, mH is the mass of a hydrogen atom, mN is the mass of a neutron, and M is the mass of the nucleus.

In the mass number range A = 30 to 170, the binding energy per nucleon is nearly constant because the nuclear force between nucleons is nearly constant. This means that the energy required to separate a nucleon from the nucleus is nearly constant in this range.

The nuclear force between nucleons is a strong force that holds the nucleus together. It is a short-range force that depends on the distance between nucleons. In the mass number range A = 30 to 170, the distance between nucleons is nearly constant, and so the nuclear force is nearly constant.

Therefore, the binding energy per nucleon is nearly constant in this range because the nuclear force is nearly constant. This means that the stability of the nucleus is nearly constant in this range.

**Explanation:**

The atomic number (Z) of an atom refers to the number of protons in the nucleus. Here, we will discuss why the correct answer is option 'D' and explain the significance of atomic number in an atom.

**Atomic Number (Z):**

The atomic number of an atom is a fundamental property that determines its identity and place in the periodic table. It is denoted by the symbol 'Z'. Each element on the periodic table has a unique atomic number.

**Protons in the Nucleus:**

Protons are subatomic particles that carry a positive charge. They are located in the nucleus of an atom, which is the central core of the atom. The number of protons in the nucleus is equal to the atomic number of the atom.

**Electrons in the Atom:**

Electrons are subatomic particles that carry a negative charge. They orbit around the nucleus in specific energy levels or shells. The number of electrons in a neutral atom is equal to the number of protons, ensuring that the atom has a balanced charge overall.

**Neutrons in the Nucleus:**

Neutrons are subatomic particles that have no charge (they are electrically neutral). They are also located in the nucleus along with protons. The number of neutrons in an atom can vary, resulting in different isotopes of the same element. Isotopes have the same atomic number (same number of protons) but different mass numbers (different number of neutrons).

**Significance of Atomic Number:**

The atomic number is a crucial characteristic of an atom because it determines the element's identity. Elements are organized in increasing order of their atomic numbers on the periodic table. For example, hydrogen has an atomic number of 1, helium has an atomic number of 2, and so on.

The atomic number defines the unique properties and behavior of an element. It determines the number of electrons in the atom, which influences the atom's chemical reactivity and bonding. It also provides information about the element's position in the periodic table, its atomic mass, and its isotopes.

Therefore, the correct answer to the given question is option 'D' – the atomic number (Z) of the nucleus represents the number of protons in it.

Option d
When H and He in sun undergoes fusion large amount of heat is released.

This is because in most chemical reactions only electrons participate. the nucleons have little role in chemical reactions

In nuclear fusion, two or more small nuclei combine to form a single larger nucleus, a neutron, and a tremendous amount of energy. Nuclear fusion of hydrogen to form helium occurs naturally in the sun and other stars. It takes place only at extremely high temperatures.

Since gamma rays carry energy that's why they are electromagnetic waves.

Excluding the lighter nuclei, the average binding energy per nucleon is about 8 MeV. The maximum binding energy per nucleon occurs at around mass number A = 50, and corresponds to the most stable nuclei.

Density of Nuclear Matter

The density of nuclear matter refers to the mass per unit volume of the nucleus of an atom.

It is independent of the number of nucleons in the nucleus because the volume of the nucleus is proportional to the cube of the radius, while the number of nucleons is proportional to the cube of the radius. Therefore, the density remains constant regardless of the number of nucleons.

The density of nuclear matter is estimated to be around 2.3 x 10^17 kg/m^3, which is much higher than the density of ordinary matter.

The high density of nuclear matter is due to the strong nuclear force that binds the protons and neutrons together in the nucleus.

Conclusion

Therefore, the correct answer to the given question is option 'A', i.e., the density of nuclear matter is independent of the number of nucleons in the nucleus.

Because the mass of the nucleus is at the centr of the nucleus and the density is also same as measured from the centr..

C Mass no Remains same ,there is an increase of +1 unit in atomic no

Artificial Disintegration with Alpha Particles and the Discovery of Neutron

The artificial disintegration of atomic nuclei using alpha particles played a crucial role in the discovery of the neutron. Among the given options, it was the element Beryllium (Be) that led to this significant breakthrough.

Artificial Disintegration with Alpha Particles:

Artificial disintegration involves bombarding atomic nuclei with high-energy particles to induce nuclear reactions. In the early 1930s, James Chadwick conducted experiments where he bombarded various elements with alpha particles, consisting of two protons and two neutrons.

Discovery of Neutron:

During his experiments, Chadwick focused on the element Beryllium (Be). When alpha particles were directed at beryllium, some of the alpha particles were deflected, while others penetrated the target material. However, Chadwick noticed that a small fraction of the alpha particles experienced a significant deflection and lost most of their energy.

Explanation:

Chadwick hypothesized that these highly deflected particles were different from protons and electrons, which were already known at that time. He concluded that these particles had a neutral charge and a mass similar to that of a proton. Chadwick named this new particle the "neutron."

Reason for Beryllium's Role:

The reason why Beryllium was crucial to this discovery lies in its atomic structure. Beryllium has a relatively low atomic number and a light nucleus, making it easier for alpha particles to penetrate its nucleus. When an alpha particle approaches the beryllium nucleus, it can interact with one of the protons or neutrons.

Interaction with Nucleus:

In the case of beryllium, the interaction between the alpha particle and the nucleus can result in the release of a neutron. This process is known as "neutron emission" or "neutron disintegration." The newly formed neutron, being neutral, does not experience any significant deflection when passing through the surrounding material, unlike the positively charged alpha particles.

Significance:

The discovery of the neutron was significant as it completed the understanding of the atomic nucleus. It provided a better understanding of the atomic structure and the forces that hold the nucleus together. Additionally, the neutron's neutral charge made it an essential component in the development of nuclear power and atomic weapons.

Conclusion:

In conclusion, the artificial disintegration of atomic nuclei with alpha particles, specifically in the case of beryllium, led to the discovery of the neutron. This discovery expanded our understanding of atomic structure and had profound implications in various scientific and technological advancements.

Atom of same element, contain same number of protons, they differ in number of neutrons .
This is known as isotope .
Therefore we can conclude that answer is [ B ]

The decay of free neutrons is energy feasible because the mass of a neutron is greater than the sum of the masses of the proton and electron it decays into. But where a neutron is paired with a proton its decay is not energy feasible and thus such neutrons within nuclei are stable.

The high temperature gives the hydrogen atoms enough energy to overcome the electrical repulsion between the protons. Fusion requires temperatures about 100 million Kelvin (approximately six times hotter than the sun's core). At these temperatures, hydrogen is a plasma, not a gas.

Hydrogen bomb or H-bomb, weapon deriving a large portion of its energy from the nuclear fusion of hydrogen isotopes. In an atomic bomb, uranium or plutonium is split into lighter elements that together weigh less than the original atoms, the remainder of the mass appearing as energy. Unlike this fission bomb, the hydrogen bomb functions by the fusion, or joining together, of lighter elements into heavier elements. The end product again weighs less than its components, the difference once more appearing as energy. Because extremely high temperatures are required in order to initiate fusion reactions, the hydrogen bomb is also known as a thermonuclear bomb. 

CCCC

Explanation:
The wrong statement among the given options is option B: "The fuel required for fusion is readily available in abundance from seawater."

Reason:
- While it is correct that a thermonuclear fusion reactor is better than a fission reactor for several reasons, including higher energy release and less radioactive waste production, the availability of fuel from seawater is not accurate.
- Fusion reactions require isotopes of hydrogen, such as deuterium and tritium, as fuel. Deuterium can be extracted from seawater, but tritium is a radioactive isotope that is not naturally abundant and needs to be produced artificially.
- Tritium can be produced by exposing lithium to neutron radiation, which can be generated by a fission reactor or a fusion reactor itself. However, the process of producing tritium is not as straightforward as extracting deuterium from seawater.
- Tritium is also highly radioactive and has a short half-life, which means it requires careful handling and containment. It cannot be easily stored or transported.
- Therefore, the fuel required for fusion reactions is not readily available in abundance from seawater, as stated in option B.

Correct statements:
a) For the same mass of substances involved, a fusion reaction releases much more energy than a fission reaction.
- This is true. Fusion reactions release a tremendous amount of energy, several times more than fission reactions. The fusion of hydrogen atoms into helium is the same process occurring in the Sun and other stars, which produces immense amounts of energy.

c) A fusion reaction can be much more easily controlled than a fission reaction.
- This is true. Fusion reactions require extremely high temperatures and pressures to sustain, and if these conditions are not maintained, the reaction will cease. This inherent stability makes fusion reactions more easily controllable than fission reactions, which can lead to runaway chain reactions if not properly regulated.

d) A fusion reaction produces almost no radioactive waste.
- This is true. Fusion reactions do not produce long-lived radioactive waste like fission reactions. The only radioactive byproduct of fusion is tritium, which has a relatively short half-life and can be managed safely.

In summary, option B is the wrong statement because the fuel required for fusion reactions is not readily available in abundance from seawater.

All of these