Physics Modern Physics questions from JEE Main 2012.
A diatomic molecule is made of two masses $m_1$ and $m_2$ which are separated by a distance $r$. If we calculate its rotational energy by applying Bohr's rule of angular momentum quantization, its energy will be given by ( $n$ is an integer)
A doubly ionised $\mathrm{Li}$ atom is excited from its ground $\operatorname{state}(n=1)$ to $n=3$ state. The wavelengths of the spectral lines are given by $\lambda_{32}, \lambda_{31}$ and $\lambda_{21}$. The ratio $\lambda_{32} / \lambda_{31}$ and $\lambda_{21} / \lambda_{31}$ are, respectively
A hypothetical atom has only three energy levels. The ground level has energy, $E_1=-8 \mathrm{eV}$. The two excited states have energies, $E_2=-6 \mathrm{eV}$ and $E_3=-2 \mathrm{eV}$. Then which of the following wavelengths will not be present in the emission spectrum of this atom?
Assume that a neutron breaks into a proton and an electron. The energy released during this process is (Mass of neutron $=1.6725 \times 10^{-27} \mathrm{~kg} ;$ mass of proton $=1.6725 \times 10^{-27} \mathrm{~kg} ;$ mass of electron $=9 \times 10^{-31}$ $\mathrm{kg})$
Hydrogen atom is excited from ground state to another state with principal quantum number equal to $4$. Then the number of spectral lines in the emission spectra will be
In the Rutherford experiment, $\alpha$-particles are scattered from a nucleus as shown. Out of the four paths, which path is not possible? 
Ionisation energy of Li (Lithium) atom in ground state is $5.4 \mathrm{eV}$. Binding energy of an electron in $\mathrm{Li}^{+}$ion in ground state is $75.6 \mathrm{eV}$. Energy required to remove all three electrons of Lithium (Li) atom is
Photoelectrons are ejected from a metal when light of frequency $v$ falls on it. Pick out the wrong statement from the following.
The electron of a hydrogen atom makes a transition from the $(n+1)^{\text {th }}$ orbit to the $n^{\text {th }}$ orbit. For large $\mathrm{n}$ the wavelength of the emitted radiation is proportional to
The figure shows a combination of two NOT gates and a NOR gate.  The combination is equivalent to $\mathrm{a}$
This question has Statement 1 and Statement 2. Of the four choices given after the Statements, choose the one that best describes the two Statements. Statement 1: A metallic surface is irradiated by a monochromatic light of frequency $v>v_0$ (the threshold frequency). If the incident frequency is now doubled, the photocurrent and the maximum kinetic energy are also doubled. Statement 2: The maximum kinetic energy of photoelectrons emitted from a surface is linearly dependent on the frequency of the incident light. The photocurrent depends only on the intensity of the incident light.
This question has Statement 1 and Statement 2. Of the four choices given after the Statements, choose the one that best describes the two Statements. Statement 1: A pure semiconductor has negative temperature coefficient of resistance. Statement 2: On raising the temperature, more charge carriers are released into the conduction band.
Truth table for system of four NAND gates as shown in figure is 
Which logic gate with inputs $\mathrm{A}$ and $\mathrm{B}$ performs the same operation as that performed by the following circuit? 
Which of the following Statements is correct?
Which of the plots shown in the figure represents speed $(v)$ of the electron in a hydrogen atom as a function of the principal quantum number $(n)$ ? 
Which one of the following is the Boolean expression for NOR gate?