Atoms and Nuclei · Physics · KCET
MCQ (Single Correct Answer)
If the radius of first Bohr orbit is $r$, then the radius of the second Bohr orbit will be
$$ \text { Match the following types of nuclei with examples shown } $$
$$ \begin{array}{|l|l|} \hline \text { Column-I } & \text { Column-II } \\ \hline \text { A. Isotopes } & \text { i. } \mathrm{Li}^7, \mathrm{Be}^7 \\ \hline \text { B. Isobars } & \text { ii. }{ }_8 \mathrm{O}^{18},{ }_9 \mathrm{~F}^{19} \\ \hline \text { C. Isotopes } & \text { iii. }{ }_1 \mathrm{H}^1,{ }_1 \mathrm{H}^2 \\ \hline \end{array} $$
Which of the following statements is incorrect with reference of 'Nuclear force'?
In alpha particle scattering experiment, if $v$ is the initial velocity of the particle, then the distance of closest approach is $d$. If the velocity is doubled, then the distance of closest approach becomes
The ratio of area of first excited state to ground state of orbit of hydrogen atom is
The ratio of volume of $\mathrm{Al}^{27}$ nucleus to its surface area is (Given, $R_0=1.2 \times 10^{-15} \mathrm{~m}$)
Consider the nuclear fission reaction ${ }_0^1 n+{ }_{92}^{235} \mathrm{U} \longrightarrow{ }_{56}^{144} \mathrm{Ba}+{ }_{36}^{89} \mathrm{Kr}+3{ }_0^1 n$. Assuming all the kinetic energy is carried away by the fast neutrons only and total binding energies of ${ }_{92}^{235} \mathrm{U},{ }_{56}^{144} \mathrm{Ba}$ and ${ }_{36}^{89} \mathrm{Kr}$ to be $1800 \mathrm{MeV}, 1200$ MeV and 780 MeV respectively, the average kinetic energy carried by each fast neutron is (in MeV)
The natural logarithm of the activity $R$ of a radioactive sample varies with time $t$ as shown. At $t=0$, there are $N_0$ undecayed nuclei. Then, $N_0$ is equal to [Take $e^2=7.5$ ]
In the Rutherford's alpha scattering experiment, as the impact parameter increases, the scattering angle of the alpha particle
Three energy levels of hydrogen atom and the corresponding wavelength of the emitted radiation due to different electron transition are as shown. Then,
A radioactive sample has half-life of 3 years. The time required for the activity of the sample to reduce to $$\frac{1}{5}$$th of its initial value is about
In the following equation representing $$\beta^{-}$$ decay, the number of neutrons in the nucleus $$X$$ is
$${ }_{83}^{210} \mathrm{Bi} \longrightarrow X+e^{-1}+\bar{v}$$
A nucleus with mass number 220 initially at rest emits an alpha particle. If the $$Q$$ value of reaction is $$5.5 ~\mathrm{MeV}$$. Calculate the value of kinetic energy of alpha particle
The radius of hydrogen atom in the ground state is 0.53$$\mathop A\limits^o $$. After collision with an electron, it is found to have a radius of 2.12$$\mathop A\limits^o $$, the principal quantum number $$n$$ of the final state of the atom is
In accordance with the Bohr's model, the quantum number that characterises the Earth's revolution around the Sun in an orbit of radius $$1.5 \times 10^{11} \mathrm{~m}$$ with orbital speed $$3 \times 10^4 \mathrm{~ms}^{-1}$$ is [given, mass of Earth $$=6 \times 10^{24} \mathrm{~kg}$$]
If an electron is revolving in its Bohr orbit having Bohr radius of 0.529$$\mathop A\limits^o $$, then the radius of third orbit is
Binding energy of a nitrogen nucleus $$\left[{ }_7^{14} \mathrm{~N}\right]$$, given $$m\left[{ }_7^{14} \mathrm{~N}\right]=14.00307 \mathrm{u}$$
Which of the following radiations is deflected by electric field?
A nuclear reactor delivers a power of $$10^9 \mathrm{~W}$$, the amount of fuel consumed by the reactor in one hour is
Energy of an electron in the second orbit of hydrogen atom is $$E_2$$. The energy of electron in the third orbit of $$\mathrm{He}^{+}$$ will be
The figure shows standing de-Broglie waves due to the revolution of electron in a certain orbit of hydrogen atom. Then, the expression for the orbit radius is (All notations have their usual meanings)
An electron in an excited state of $$\mathrm{Li}^{2+}$$ ion has angular momentum $$\frac{3 h}{2 \pi}$$. The de-Broglie wavelength of electron in this state is $$p \pi a_0$$ (where, $$a_0=$$ Bohr radius). The value of $$p$$ is
Which graph in the following diagram correctly represents the potential energy of a pair of nucleons as a function of their separation?
In a nuclear reactor heavy nuclei is not used as moderators because
The period of revolution of an electron revolving in nth orbit of $$\mathrm{H}$$-atom is proportional to
Angular momentum of an electron in hydrogen atom is $$\frac{3 h}{2 \pi}$$ ($$h$$ is the Planck's constant). The KE of the electron is
A beam of fast moving alpha particles were directed towards a thin film of gold. The parts $$A, B$$ and $$C$$ of the transmitted and reflected beams corresponding to the incident parts $$A, B$$ and $$C$$ of the beam are shown in the adjoining diagram. The number of alpha particles in
Two protons are kept at a separation of $$10 \mathrm{~nm}$$. Let $$F_n$$ and $$F_e$$ the nuclear force and the electromagnetic force between them
During a $$\beta^{-}$$-decay
A radio-active elements has half-life of 15 years. What is the fraction that will decay in 30 years?
Which one of the following nuclei has shorter mean life?
In Rutherford experiment, for head-on collision of $$\alpha$$-particles with a gold nucleus, the impact parameter is
Frequency of revolution of an electron revolving in $$n$$th orbit of $$\mathrm{H}$$-atom is proportional to
A hydrogen atom is ground state absorbs $$10.2 \mathrm{~eV}$$ of energy. The orbital angular momentum of the electron is increased by
The end product of decay of $${ }_{90} \mathrm{Th}^{232}$$ is $${ }_{82} \mathrm{~Pb}^{208}$$. The number of $$\alpha$$ and $$\beta$$ particles emitted are respectively