NCERT Solutions

13.1 Obtain the binding energy (in MeV ) of a nitrogen nucleus ( ${ }_{7}^{14} \mathrm{N}$ ), given $m\left({ }_{7}^{14} \mathrm{N}\right)=14.00307 \mathrm{u}$

13.2 Obtain the binding energy of the nuclei ${ }_{26}^{56} \mathrm{Fe}$ and ${ }_{83}^{209} \mathrm{Bi}$ in units of MeV from the following data: $m\left({ }_{26}^{56} \mathrm{Fe}\right)=55.934939 \mathrm{u} \quad m\left({ }_{83}^{209} \mathrm{Bi}\right)=208.980388 \mathrm{u}$

13.3 A given coin has a mass of 3.0 g . Calculate the nuclear energy that would be required to separate all the neutrons and protons from each other. For simplicity assume that the coin is entirely made of ${ }_{29}^{63} \mathrm{Cu}$ atoms (of mass 62.92960 u ).

13.4 Obtain approximately the ratio of the nuclear radii of the gold isotope ${ }_{79}^{197} \mathrm{Au}$ and the silver isotope ${ }_{47}^{107} \mathrm{Ag}$.

13.6 Suppose, we think of fission of a ${ }_{26}^{56} \mathrm{Fe}$ nucleus into two equal fragments, ${ }_{13}^{28} \mathrm{Al}$. Is the fission energetically possible? Argue by working out $Q$ of the process. Given $m\left({ }_{26}^{56} \mathrm{Fe}\right)=55.93494 \mathrm{u}$ and $m\left({ }_{13}^{28} \mathrm{Al}\right)=27.98191 \mathrm{u}$.

13.7 The fission properties of ${ }_{94}^{239} \mathrm{Pu}$ are very similar to those of ${ }_{92}^{235} \mathrm{U}$. The average energy released per fission is 180 MeV . How much energy, in MeV , is released if all the atoms in 1 kg of pure ${ }_{94}^{239} \mathrm{Pu}$ undergo fission?

13.8 How long can an electric lamp of 100 W be kept glowing by fusion of 2.0 kg of deuterium? Take the fusion reaction as ${ }_{1}^{2} \mathrm{H}+{ }_{1}^{2} \mathrm{H} \rightarrow{ }_{2}^{3} \mathrm{He}+\mathrm{n}+3.27 \mathrm{MeV}$

13.9 Calculate the height of the potential barrier for a head on collision of two deuterons. (Hint: The height of the potential barrier is given by the Coulomb repulsion between the two deuterons when they just touch each other. Assume that they can be taken as hard spheres of radius 2.0 fm .)

13.10 From the relation $R=R_{0} A^{1 / 3}$, where $R_{0}$ is a constant and $A$ is the mass number of a nucleus, show that the nuclear matter density is nearly constant (i.e. independent of $A$ ).