Neutron Mass Important Questions

---

Very Short Answers Questions [1 Mark Questions]

Ques. The mass of a neutron is _________ than the mass of a proton.

1. More
2. Less
3. Equal
4. None of the above

Ans. The correct answer is a. More

Explanation: The mass of a neutron and a proton are 1.00865 amu and 1.00727 amu respectively. Hence the mass of a neutron is more than the mass of a proton.

Ques. An atom containing 11 protons and 12 neutrons has a mass number equal to 23.

1. True
2. False

Ans. The correct answer is a. True

Explanation: Mass number = Number of protons + Number of neutrons

⇒ Mass number = 11 + 12 = 23

Ques. What is the mass of a neutron in grams?

1. 1.67492749804 x 10⁻²⁵ g
2. 1.67492749804 x 10⁻²⁴ g
3. 1.67492749804 x 10⁻²³ g
4. 1.67492749804 x 10⁻²² g

Ans. The correct answer is b. 1.67492749804 x 10⁻²⁴ g

Explanation: The mass of a neutron in grams is 1.67492749804 x 10⁻²⁴ g

Ques. What is the mass of a neutron in kilograms?

1. 1.67492749804 x 10⁻²⁷ kg
2. 1.67492749804 x 10⁻²⁸ kg
3. 1.67492749804 x 10⁻²⁹ kg
4. 1.67492749804 x 10⁻³¹ kg

Ans. The correct answer is a. 1.67492749804 x 10⁻²⁷ kg

Explanation: The mass of a neutron in kilograms is 1.67492749804 x 10⁻²⁷ kg

Ques. What is the mass of a neutron in amu?

1. 2.008665 amu
2. 3.008665 amu
3. 0.008665 amu
4. 1.008665 amu

Ans. The correct answer is d. 1.008665 amu

Explanation: The mass of a neutron in amu is 1.008665 amu.

Ques. What is the mass-energy equivalent of a neutron in MeV?

1. 939.56542052 MeV
2. 639.56542052 MeV
3. 539.56542052 MeV
4. 139.56542052 MeV

Ans. The correct answer is a. 939.56542052 MeV

Explanation: The mass-energy equivalent of a neutron is 939.56542052 MeV.

---

Short Answers Questions [2 Marks Questions]

Ques. Write the approximate mass of a proton, neutron, and electron in amu.

Ans. The mass of a proton = 1.00727 amu

The mass of a neutron = 1.00865 amu

The mass of an electron = 0.00055 amu

Ques. What is a neutron?

Ans. The neutron is a subatomic particle that has a neutral charge and a slightly larger mass than a proton. Atomic nuclei are made up of protons and neutrons.

Ques. What is Nuclear Stability?

Ans. Nuclear stability refers to the stability of the nucleus of an atom. A stable nucleus does not disintegrate on its own. Radioactive elements have unstable nuclei that spontaneously decay, generating different radiations.

Ques. What are the different types of neutrons?

Ans. The three primary types of neutrons (based on energy levels) are thermal neutrons, resonance neutrons, and fast neutrons. A thermal neutron is in thermal equilibrium with other matter and has a Maxwellian velocity distribution in exceptional cases. At 295 K, the most likely velocity is roughly 2200 m/sec, with an energy level of 0.025 eV. Intermediate neutrons are neutrons with energies ranging from 0.5 to 10 keV. A fast neutron is a type of neutron with an energy level ranging from 10 keV to 10 MeV.

Ques. What are neutrons made of?

Ans. A neutron is a type of fermion composed of one up quark and two down quarks. It is denoted by the symbols n or n_o.

Ques. What are the main components of an atomic nucleus?

Ans. Electrically charged protons and electrically neutral neutrons make up atomic nuclei. The strongest fundamental force, known as the strong force, holds them together. The nucleus accounts for less than 0.01 percent of the volume of the atom yet contains more than 99.9% of its mass.

Ques. Who discovered Neutrons?

Ans. In 1932, British physicist Sir James Chadwick discovered neutrons. For this discovery, he received the Nobel Prize in Physics in 1935.

Also Read:

---

Long Answers Questions [3 Marks Questions]

Ques. What are the properties of neutrons?

Ans. The following are the properties of a neutron

• Neutron has no charge
• The mass of a neutron is 1.67 x 10^-27 kg or 1.008665 amu.
• Being neutral, it is neither attracted nor repelled by the nucleus of the atom, so it can penetrate deep into the atom of a target.
• A neutron has a low ionizing power.
• The neutron inside the nucleus is stable.
• A free neutron i.e. outside the nucleus is unstable. The mean life of a free neutron is about 16.6 minutes.
• The speed of thermal neutrons is 2200 m/s and energy is equivalent to 0.025 eV. Thermal neutrons are most suitable for causing nuclear reactions.
• The magnetic moment of a neutron is -1.91 nuclear magnetron.

Ques. What are the applications of neutrons?

Ans. The following are the applications of neutrons

• They allow scientists and engineers to investigate materials, exposing their atomic structures, dynamics, and magnetic characteristics to determine how to make the materials stronger, lighter, and perform better.
• Neutron scattering experiments play an important role in examining the characteristics of new materials, which are essential to advancements in energy, nanotechnology, transportation, communication, and many other fields.
• The penetrating power and non-destructive nature of neutrons provide unique opportunities for non-invasive atomic scale testing to evaluate residual stress, deformation, and the microstructure of engineering components.

Ques. What is the difference between Atomic Number and Atomic Mass?

Ans. The differences between atomic number and atomic mass are

---

Very Long Answers Questions [5 Marks Questions]

Ques. The masses of a neutron and a proton are 1.0087 a.m.u and 1.0073 a.m.u respectively. If the neutrons and protons combine to form a helium nucleus (alpha particles) of mass 4.0015 a.m.u. What will be the binding energy of the helium nucleus?

Ans. Given

• The mass of the neutron, m_n = 1.0087 a.m.u
• The mass of the proton, m_p = 1.0073 a.m.u
• The mass of the helium nucleus, M_He = 4.0015 a.m.u

A helium nucleus contains 2 neutrons and 2 protons, therefore the mass of the constituent particles of the the helium is

M’ = 2m_n + 2m_p

⇒ M’ = (2 x 1.0087) + (2 x 1.0073) = 2 (1.0087 + 1.0073)

⇒ M’ = 4.032 amu

Mass defect, ΔM = M’ - M_He

⇒ ΔM = 4.032 - 4.0015 = 0.0305 amu

Therefore, the binding energy, (BE) = ΔM x 931 MeV

⇒ (BE) = 0.0305 x 931 = 28.4 MeV

Ques. Calculate the binding energy of ₈O¹⁶ nucleus. Given

1. The mass of ₈O¹⁶ = 15.994914 amu
2. Mass of proton = 1.007825 amu
3. Mass of neutron = 1.008665 amu

Ans. ₈O¹⁶ contains 8 protons and 8 neutrons.

Given

• The mass of ₈O¹⁶, M= 15.994914 amu
• Mass of proton, m_p = 1.007825 amu
• Mass of neutron, m_n = 1.008665 amu

The mass of the constituents of ₈O¹⁶ nucleus is given by

M’ = 8m_n + 8m_p

⇒ M’ = 8(m_n + m_p)

⇒ M’ = 8(1.00866 + 1.007825) = 16.13192 amu

Mass defect is given by

Δm = mass of the constituents of the nucleus - mass of the nucleus

⇒ Δm = 16.13192 - 15.994914 = 0.137 amu

Therefore, the binding energy of ₈O¹⁶ nucleus is given by

E = Δm x 931 MeV

⇒ E = 0.137 x 931 = 127.55 MeV

Ques. Calculate the binding energies of ₁₇C³⁵ and ₂₆Fe⁵⁶. Given

1. Mass of ₁₇C³⁵ = 34.980 amu
2. Mass of ₂₆Fe⁵⁶= 55.934932 amu
3. Mass of proton = 1.007825 amu
4. Mass of neutron = 1.008665 amu

Also, find their binding energy per nucleon. State which of the nuclei is more stable.

Ans. Given

• Mass of ₁₇C³⁵ , M_Cl = 34.980 amu
• Mass of ₂₆Fe⁵⁶, M_Fe = 55.934932 amu
• Mass of proton, m_p = 1.007825 amu

• Mass of neutron, m_n = 1.008665 amu

A ₁₇C³⁵ nucleus has 17 protons and 18 neutrons. Therefore the mass of the constituent particle of ₁₇C³⁵ nucleus is

M’_Cl = 17m_p + 18m_n

⇒ M’_Cl = (17 x 1.007825) + (18 x 1.008665)

⇒ M’_Cl = 35.288995 amu

Mass defect, ΔM = M’_Cl – M_Cl

⇒ ΔM = 35.288995 - 34.980 = 0.308995 amu

Binding energy of ₁₇C³⁵ , (BE)_Cl = ΔM x 931 MeV

⇒ (BE)_Cl = 0.308995 x 931 = 287.67 MeV

Binding energy per nucleon = 287.67/35 = 8.219 MeV/nucleon

A ₂₆Fe⁵⁶nucleus has 26 protons and 30 neutrons. Therefore the mass of the constituent particle of ₂₆Fe⁵⁶nucleus is

M’_Fe = 26m_p + 30m_n

⇒ M’_Fe = (26 x 1.007825) + (30 x 1.008665)

⇒ M’_Fe = 56.4634 amu

Mass defect, ΔM = M’_Fe – M_Fe

⇒ ΔM = 56.4634 - 55.934932 = 0.528468 amu

Binding energy of ₂₆Fe⁵⁶, (BE)_Fe = ΔM x 931 MeV

⇒ (BE)_Cl = 0.528468 x 931 = 492.004 MeV

Binding energy per nucleon = 492.004/56 = 8.78 MeV/nucleon

Since the binding energy per nucleon of 26Fe56 nucleus is greater than the ₁₇C³⁵ nucleus, hence ₂₆Fe⁵⁶ nucleus is more stable.

---

Previous Year Questions

1. Extraction of metal from the ore cassiterite involves...[JEE Advanced 2011]
2. Commonly used vectors for human genome sequencing are...[NEET UG 2014]
3. Interfascicular cambium and cork cambium are formed due to​..
4. Pneumotaxic centre is present in​...[UP CPMT 2007]
5. Reaction of HBr with propene in the presence of peroxide gives….[NEET UG 2004]
6. Assuming the expression for the pressure exerted by the gas on the walls of the container, it can be shown that pressure is...[MHT CET 2016]
7. Which among the following is the strongest acid?...[TS EAMCET 2017]
8. Isopropyl alcohol on oxidation forms​..
9. A vector is not changed if​..
10. Which of the following arrangements does not represent the correct order of the property stated against it?...[JEE Main 2013]

For Latest Updates on Upcoming Board Exams, Click Here: https://t.me/class_10_12_board_updates

---

Check-Out: