Chapter 7 – Atomic Nucleus

Book Name	: Madhyamik Physical Science And Environment
Subject	: Physical Science
Class	: 10 (Madhyamik)
Publisher	: Oriental Book Company  Pvt. Ltd
Chapter Name	: Atomic Nucleus

Multiple-choice questions

Question 1

Binding energy is

1. Bonding between two atoms
2. Fission of a covalent bond
3. Binding among the nucleons in the nucleus
4. none of these

Answer

(c) Binding among the nucleons in the nucleus

Question 2

Nuclear fission is initiated by

1. slow neutron
2. fast neutron
3. by proton
4. by a-particle

Answer

(a) slow neutron

Question 3

Nuclear energy is

1. renewable
2. not renewable
3. sometimes renewable
4. it is a matter of debate

Answer

(a) not renewable

Explanation:

Nuclear energy is not renewable. Although nuclear fuel, such as uranium, is abundant in the earth’s crust, it is not considered a renewable resource because it is a finite resource that cannot be replenished within a human lifespan.

Question 4

The radioactive isotope used in atom bomb is

1. Ra-226
2. U-238
3. C-14
4. U-235

Answer

(d) U-235

Explanation:

The radioactive isotope used in an atomic bomb is uranium-235 (U-235). This isotope is relatively unstable and can undergo fission when it absorbs a neutron, releasing a large amount of energy in the process.

Question 5

Source of energy of sun is

1. Fission reaction
2. Fusion reaction
3. Spalation reaction
4. none of these

Answer

(b) fusion reaction

Explanation:

The source of energy of the sun is fusion reaction, specifically the fusion of hydrogen nuclei (protons) into helium nuclei in the sun’s core.

Answer the following questions

Question 1

How nuclear energy can be obtained? 

Answer

Nuclear energy can be obtained through nuclear fission or fusion, where the energy released from the splitting of atoms or merging of atomic nuclei can be harnessed for various applications, including generating electricity.

Question 2

What is mass defect? 

Answer

Mass defect refers to the difference between the actual mass of an atomic nucleus and the sum of the masses of its constituent protons and neutrons, due to the conversion of mass into energy during nuclear binding.

Question 3

Give an example of a nuclear plant accident. 

Answer

The Chernobyl disaster, which occurred in 1986 at the Chernobyl Nuclear Power Plant in Ukraine, is an example of a nuclear plant accident.

Question 4

Mention one advantage of nuclear fission. 

Answer

One advantage of nuclear fission is that it does not emit greenhouse gases such as carbon dioxide, which contributes to climate change, making it a relatively clean source of energy compared to fossil fuels.

Question 5

What is the cause of the Fukushima nuclear power plant accident?

Answer

The Fukushima nuclear power plant accident was caused by a 9.0 magnitude earthquake and subsequent tsunami that damaged the plant’s cooling systems, leading to multiple nuclear reactor meltdowns and releases of radioactive materials.

Supply the missing word from these in the brackets

Question

1. Bombardment of one U-235 with one neutron produces ____ neutrons. (3 / 4) 
2. Chernobyl located in ____. (Japan / Ukraine) 
3. One gram U-235 ____ generates KWh of electric energy. (20,000 / 11,000) 
4. The heat required to start the fusion reaction is supplied by ____ reaction. (Fission / Spalation)
5. The fusion reaction ____ controlled. (can be / cannot be)

Answer

Short Answer Type Questions

Question 1

What is a mass defect? How it is related to energy?

Answer

Mass defect refers to the difference between the mass of an atomic nucleus and the sum of the masses of its constituent protons and neutrons. The difference is due to the conversion of mass into energy during nuclear binding, as predicted by Einstein’s famous equation E=mc².

Question 2

Why energy is released in a nuclear fission reaction?

Answer

Energy is released in a nuclear fission reaction due to the conversion of a small amount of the mass of the nucleus into energy, according to Einstein’s equation E=mc². This occurs because the total mass of the products of the fission reaction is less than the mass of the original nucleus, resulting in a mass defect.

Question 3

Discuss the consequences of dropping atomic bombs on Hiroshima and Nagasaki. 

Answer

The consequences of dropping the atomic bombs on Hiroshima and Nagasaki were catastrophic. The immediate effects of the bombs included massive destruction, loss of life, and radiation sickness, while the long-term effects included increased cancer rates and genetic mutations.

Question 4

Mention the peaceful use of nuclear energy. 

Answer

Nuclear energy has a variety of peaceful uses, including generating electricity, powering spacecraft, and medical applications such as cancer treatments and imaging technologies. It can also be used for industrial purposes such as producing hydrogen fuel and desalinating water.

Question 5

Discuss the principle of the nuclear power plant. 

Answer

The principle of a nuclear power plant is to produce heat from nuclear reactions, typically through nuclear fission, and then use that heat to generate steam to power turbines, which in turn generate electricity.

Question 6

What are the advantages and disadvantages of generating electricity by nuclear fission? 

Answer

Advantages:

1. High energy density with low fuel consumption
2. Low greenhouse gas emissions

Disadvantages:

1. Nuclear waste disposal issues
2. High cost of construction and maintenance

Question 7

Write notes on Fukushima nuclear power plant accident. 

Answer

The Fukushima nuclear power plant accident was a disaster that occurred in 2011 in Japan due to an earthquake and tsunami. It resulted in multiple reactor meltdowns, the release of radioactive materials, and forced evacuations, making it one of the worst nuclear disasters in history.

Question 8

Between fission and fusion reactions which one is preferred for energy production?

Answer

Both fission and fusion reactions have the potential to produce energy, but currently, fission is preferred for energy production as it is more developed and established technology. Fission reactions are currently used in nuclear power plants to generate electricity, while fusion reactions are still being researched and developed as a potential future source of energy.

Long Answer (LA) type Questions

Question 1

Mention some points of merits and demerits of the use of nuclear energy. 

Answer

Merits:

1. Produces large amounts of energy with small amounts of fuel.
2. Can reduce reliance on fossil fuels.
3. Low greenhouse gas emissions compared to fossil fuels.
4. Can be used for various applications such as electricity generation, medical diagnosis and treatment, and research.

Demerits:

1. Risk of nuclear accidents with catastrophic consequences.
2. The disposal of radioactive waste is a major concern.
3. High costs associated with building and maintaining nuclear power plants.
4. The proliferation of nuclear weapons is a potential risk.

Question 2

Write notes on nuclear binding energy. 

Answer

Nuclear binding energy refers to the energy required to separate the nucleons in a nucleus. It is the energy that holds the nucleus together. The mass of a nucleus is always less than the total mass of its individual nucleons, and the difference between the two masses is called the mass defect. This mass defect is converted into binding energy, which is released when a nucleus is formed from individual nucleons, and this energy can be harnessed for various applications, including nuclear power production.

Question 3

Write notes on fission reaction. 

Answer

In fission reactions, the nucleus of an atom is split into two smaller nuclei, along with the release of a large amount of energy in the form of heat and radiation. This process is typically initiated by the absorption of a neutron by a heavy nucleus, such as uranium-235. Fission reactions are used in nuclear power plants to generate electricity, but can also be harnessed for destructive purposes in nuclear weapons.

Question 4

What is the source of energy in the Sun?

Answer

The source of energy in the sun is the nuclear fusion of hydrogen nuclei (protons) into helium. This process releases an enormous amount of energy in the form of light and heat. The fusion reaction occurs at the sun’s core, where the temperature and pressure are high enough to overcome the electrostatic repulsion between positively charged protons.