Question

If in a nuclear fusion process, the masses of the fusing nuclei be $${m_1}$$ and $${m_2}$$ and the mass of the resultant nucleus be $${m_3},$$ then

A. $${m_3} = {m_1} + {m_2}$$
B. $${m_3} = \left| {{m_1} - {m_2}} \right|$$
C. $${m_3} < \left( {{m_1} + {m_2}} \right)$$  
D. $${m_3} > \left( {{m_1} + {m_2}} \right)$$
Answer :   $${m_3} < \left( {{m_1} + {m_2}} \right)$$
Solution :
In a nuclear fusion, when two light nuclei of different masses are combined to form a stable nucleus, then some mass is lost and appears in the form of energy, called the mass defect. So, the mass of resultant nucleus is always less than the sum of masses of initial nuclei i.e.,
$${m_3} < \left( {{m_1} + {m_2}} \right)$$

Releted MCQ Question on
Modern Physics >> Atoms or Nuclear Fission and Fusion

Releted Question 1

The equation
$$4_1^1{H^ + } \to _2^4H{e^{2 + }} + 2{e^ - } + 26MeV$$       represents

A. $$\beta $$ -decay
B. $$\gamma $$ -decay
C. fusion
D. fission
Releted Question 2

Fast neutrons can easily be slowed down by

A. the use of lead shielding
B. passing them through water
C. elastic collisions with heavy nuclei
D. applying a strong electric field
Releted Question 3

In the nuclear fusion reaction
$$_1^2H + _1^3H \to _2^4He + n$$
given that the repulsive potential energy between the two nuclei is $$ \sim 7.7 \times {10^{ - 14}}J,$$    the temperature at which the gases must be heated to initiate the reaction is nearly
[Boltzmann’s Constant $$k = 1.38 \times {10^{ - 23}}J/K$$    ]

A. $${10^7}K$$
B. $${10^5}K$$
C. $${10^3}K$$
D. $${10^9}K$$
Releted Question 4

The binding energy per nucleon of deuteron $$\left( {_1^2H} \right)$$ and helium nucleus $$\left( {_2^4He} \right)$$  is $$1.1\,MeV$$  and $$7\,MeV$$  respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is

A. $$23.6\,MeV$$
B. $$26.9\,MeV$$
C. $$13.9\,MeV$$
D. $$19.2\,MeV$$

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