Nuclear Fusion

Q. Heavy stable nuclei have more neutrons than protons. This is because of the fact that

1. neutrons are heavier than protons.
2. neutrons decay into protons through beta decay.
3. electrostatic force between protons are repulsive.
4. nuclear forces between neutrons are weaker than that between protons.

Q.

Is the sun powered by nuclear fission?

Q.

A black body radiates energy at the rate of E $W/m^2$ at a high temperature TK. When the temperature is reduced to $\frac{T}{2}K$, the radiant energy will be

1. 

2. 

3. 

4. 

Q. In a hydrogen atom, the electron and proton are bound at a distance of about $0.53\stackrel{o}{A}$:

A) Estimate the potential energy of the system in $eV$, taking the zero of the potential energy at infinite separation of the electron from proton.

B) What is the minimum work required to free the electron, given that its kinetic energy in the orbit is half the magnitude of potential energy obtained in (a)?

C) What are the answers to (a) and (b) above if the zero of potential energy is taken at $1.06\stackrel{o}{A}$ separtion?

Q. How long can an electric lamp of 100W be kept glowing by fusion of2.0 kg of deuterium? Take the fusion reaction as2 2 31 1 2 H+ H He+n+3.27 MeV

Q. A) The total energy of an electron in the first excited state of the hydrogen atom is about $-3.4eV$. What is the kinetic energy of the electron in this state?

B) The total energy of an electron in the first excited state of the hydrogen atom is about $–3.4eV$. What is the potential energy of the electron in this state?

C) The total energy of an electron in the first excited state of the hydrogen atom is about $-3.4eV$. How would the value of total energy change if the choice of the zero of potential energy is changed?

Q. Consider aiming a beam of free electrons towards free protons. When they scatter, an electron and a proton cannot combine to produce a \(H\)-atom,

Q. $O_2$ molecule consists of two oxygen atoms. In the molecule, nuclear force between the nuclei of the two atoms

1. is as important as electrostatic force for binding the two atoms.
   
2. cancels the repulsive electrostatic force between the nuclei.
   
3. is not important because oxygen nucleus have equal number of neutrons and protons.
4. is not important because nuclear forces are short ranged.
   

Q.

Consider the D−T reaction (deuterium−tritium fusion)

(a) Calculate the energy released in MeV in this reaction from the data:

= 2.014102 u

= 3.016049 u

(b)Consider the radius of both deuterium and tritium to be approximately 2.0 fm. What is the kinetic energy needed to overcome the coulomb repulsion between the two nuclei? To what temperature must the gas be heated to initiate the reaction? (Hint: Kinetic energy required for one fusion event =average thermal kinetic energy available with the interacting particles = 2(3kT/2); k = Boltzman’s constant, T = absolute temperature.)

Q. The mass of an $\alpha -$particle is

1. equal to mass of four protons
2. equal to mass of four neutrons
3. less than the sum of masses of two protons and two neutrons
4. equal to sum of masses of two protons and two neutrons

Q.

Energy generation in stars is mainly due to

1. Chemical reactions

2. Fission of heavy nuclei

3. Fusion of light nuclei

4. Fusion of heavy nuclei

Q. Fusion reaction is given by ${}_6^{12}C{+}_6^{12}C{\to }_{10}^{20}Ne{+}_2^{4}He$.
If B.E. per nucleon for ${}_6^{12}C$ is X, B.E. per nucleon for ${}_{10}^{20}Ne$ is Y and B.E. per nucleon for ${}_2^{4}He$ is Z, then Q value of reaction is

1. $24X-20Y-6Z$
2. $Y+Z-X$
3. $24X-10Y-2Z$
4. $20Y+4Z-24X$

Q. Consider two deuterons moving towards each other with equal speeds in a deuteron gas.Their kinetic energies (when they are widely separated) shoud be such that the closest separation between them becomes 2 fm. Assume that the nuclear force is not effective for separations greater than 2 fm. At what temperature will the deuterons have this kinetic energy on an average?

1. 500 K
2. 10000 K
3. 
4. 

Q. In fusion reaction ${}_1^{2}H{+}_1^{2}H{\to }_2^{3}He{+}_0^{1}n,$ the masses of deuteron, helium and neutron expressed in $\text{amu}$ are $2.015,3.017$ and $1.009$ respectively. If $1\text{kg}$ of deuterium undergoes complete fusion, find the amount of total energy released $(1\text{amu}{c}^2=931.5\text{MeV})$.

1. $9\times {10}^{14}\text{J}$
2. $9\times {10}^{15}\text{J}$
3. $9\times {10}^{16}\text{J}$
4. $9\times {10}^{13}\text{J}$

Q. The purpose of control rods in a fission reactor is to

1. cool down the reactor
2. prevent oxygen from reaching the fuel
3. absorb electrons emitted in fission proces
4. absorb neutrons generated in the fission process

Q.

The energy of the sun is produced by the _______.

Q. Fusion reaction is possible at high temperature because -

1. Atoms are ionised at high temperature
2. Molecules break-up at high temperature
3. Nuclei break-up at high temperature
4. Kinetic energy is high enough to overcome repulsion between nuclei.

Q. The energy equivalent of $1\text{kg}$ of a substance is

1. $4.5\times {10}^{15}\text{J}$
2. $4.5\times {10}^{16}\text{J}$
3. $9\times {10}^{13}\text{J}$
4. $9\times {10}^{16}\text{J}$

Q. In a thermo-nuclear reaction, ${10}^{-3}\text{kg}$ of hydrogen is converted into $0.99\times {10}^{-3}\text{kg}$ of helium. If the efficiency of the generator is $50\%$ then the electrical energy generated in $\text{kWh}$ is-

1. $1.3\times {10}^5$
2. $1.25\times {10}^5$
3. $1.5\times {10}^5$
4. ${10}^5$

Q. Why do stable nuclei never have more protons than neutrons?

Q. Daily food intake of a human adult is equivalent ${10}^7\text{J}$. Its value in electron volt is

1. $1.6\times {10}^{-25}\text{eV}$
2. $6.25\times {10}^{+25}\text{eV}$
   
3. $3.25\times {10}^{-20}\text{eV}$
4. $6\times {10}^{+20}\text{eV}$

Q. It is proposed to use the nuclear fusion reaction ${}_1^{2}H+{}_1^{2}H\to {}_2^{4}He$ in a nuclear reactor with an electrical power rating of 200 MW. If the energy from the above reaction is used with 25 percent efficiency in the reactor, how many grams of deuterium fuel will be needed per day? (The masses of ${}_1^{2}H$ and ${}_2^{4}He$ are $2.0141\text{amu}$ and $4.0026\text{amu}$ respectively.)

1. $290\text{gm}$
2. $230\text{gm}$
3. $100\text{gm}$
4. $130\text{gm}$

Q.

In fusion, the percentage of mass converted into energy is about

1. $0.01\%$

2. $0.1\%$

3. $1\%$

4. $10\%$

Q.

Action of heat on potassium permanganate at $746\mathrm{K}$ results in formation of ________.

Q.

In the nuclear reaction:

${}_{92}{\text{U}}^{235}+\text{X}{\to }_{56}{\text{Ba}}^{141}{+}_{36}{\text{Kr}}^{92}+3\left({}_0{n}^1\right)+\text{Energy}$, $\text{X}$ stands for

1. electron

2. proton

3. neutron

4. none of these

Q. The ground state energy of hydrogen atom is $-13.6eV$. What are the kinetic and potential energies of the electron in this state?

Q. The temperature of a black body increases from $T$ to $2T$. The factor by which the rate of emission will increase

1. $2$
2. $4$
3. $8$
4. $16$

Q. From the following equations, pick out the possible nuclear fusion reaction

1. ${}_6{C}^{13}+{}_1{H}^1⟶{}_6{C}^{14}+4.3MeV$

2. ${}_6{C}^{12}+{}_1{H}^1⟶{}_7{N}^{13}+2MeV$
3. ${}_7{N}^{14}+{}_1{H}^1⟶{}_8{O}^{16}+7.3MeV$
4. ${}_{92}{U}^{235}+{}_0{n}^1⟶{}_{54}X{e}^{140}{+}_{38}S{r}^{94}+2{(}_0{n}^1)+\gamma +200MeV$

Q.

Is fission stronger than fusion?

Q. What Is exchange energy