In an element with atomic number $(Z) 25$, the number of electrons with $(n+l)$ value equal to 3 and 4 are $x$ and $y$ respectively. The value of $(x+y)$ is

The wavelength of a particular electron transition for $\mathrm{He}^{+}$is 100 nm . The wavelength (in $\AA$ ) of H atom for the same transition is

The energy of second Bohr orbit of hydrogen atom is -3.4 eV . The energy of the fourth Bohr orbit of the $\mathrm{He}^{+}$ ion will be

$a, b, c, d$ are electromagnetic radiations. Frequencies of $a, b$ are $3 \times 10^{15} \mathrm{~Hz}, 2 \times 10^{14} \mathrm{~Hz}$, respectively, whereas wavelength of $c, d$ are $400 \mathrm{~nm}, 750 \mathrm{~nm}$, respectively. The increasing order of their energies is

The number of electrons with magnetic quantum number, $m_l=0$ in the elements with atomic numbers $Z=24$ and $Z=29$ are respectively.

Which of the following represents the wavelength of spectral line of Balmer series of $\mathrm{He}^{+}$ion?

$(R=$ Rydberg constant, $n>2)$

The work functions (in eV ) of $\mathrm{Mg}, \mathrm{Cu}, \mathrm{Ag}, \mathrm{Na}$ respectively are $3.7,4.8,4.3,2.3$. From how many metals, the electrons will be ejected if their surfaces are irradiated with an electromagnetic radiation of wavelength 300 nm ?

$\left(h=6.6 \times 10^{-34} \mathrm{Js}, 1 \mathrm{eV}=1.6 \times 10^{-19} \mathrm{~J}\right)$

The uncertainty in the velocities of two particles $A$ and $B$ are 0.03 and $0.01 \mathrm{~ms}^{-1}$ respectively. The mass of $B$ is four times to the mass of $A$. The ratio of uncertainties in their positions is

The total maximum number of electrons possible in $3 d$. $6 d, 5 s$ and $4 f$ orbitals with $m_l$ (magnetic quantum number) value -2 is

The radius of fourth orbit in $\mathrm{He}^{+}$ion is ' $R_1{ }^{\prime} \mathrm{pm}$ and radius of third orbit in $\mathrm{Li}^{2+}$ ion is ' $R_2{ }^{\prime} \mathrm{pm}$. The value of ( $R_1-R_2$ ) in pm is

The de-Broglie wavelengths of two fast moving particles $X, Y$ are $1 \mathrm{~nm}, 3 \mathrm{~nm}$ respectively. Mass of $X$ is nine times the mass of $Y$. The ratio of kinetic energies of $X, Y$ is

The difference between the radii of 3rd and 2nd orbit of H -atom is $x \mathrm{pm}$. The difference between the radii of 4th and 3rd orbit of $\mathrm{Li}^{2+}$ ion is $y$ pm. $y: x$ is equal to

The de-Broglie wavelength of an electron in the third Bohr orbit of H -atom is

The wavenumber of the first line $\left(n_2=3\right)$ in the Balmer series of hydrogen is overline $\bar{v}_1 \mathrm{~cm}^{-1}$. What is the wavenumber (in $\mathrm{cm}^{-1}$ ) of the second line ( $n_2=4$ ) in the Balmer series of $\mathrm{He}^{+}$?

Which of the following sets of quantum numbers is not possible for the electron?

The uncertainty in the position of electron $(\Delta x)$ is approximately 100 pm . The uncertainty in momentum (in $\mathrm{kg} \mathrm{ms}^{-1}$ ) of an electron $\left[h=6.626 \times 10^{-34} \mathrm{Js}\right]$

Which of the following statements are correct?

I. The energy of hydrogen atom in its ground state is -13.6 eV .

II. On the basis of Bohr's model, the radius of the 3rd orbit of hydrogen atom is 158.7 pm .

III. The order of radius of the first orbit of $\mathrm{H}, \mathrm{He}^{+}, \mathrm{Li}^{2+}$ and $\mathrm{Be}^{3+}$ is $\mathrm{H}>\mathrm{He}^{+}>\mathrm{Li}^{2+}>\mathrm{Be}^{3+}$.

When a metal surface is irradiated with light of frequency $x \mathrm{~Hz}$, the kinetic energy of emitted photoelectrons is $z \mathrm{~J}$. When the same metal is irradiated with light of frequency $y \mathrm{~Hz}$, the kinetic energy of emitted electrons is $z / 3 \mathrm{~J}$. What is threshold frequency (in Hz ) of metal?

Identify the correct statements from the following

I. Isotopes of an element show different chemical behaviour.

II. Lyman series of lines of hydrogen spectrum appear in UV region.

III. The oscillating electric and magnetic field components of electromagnetic radiation are perpendicular to each other and both are perpendicular to the direction of propagation of radiation.

The sum of number of angular nodes and radial nodes for $4 d$-orbital is

If the position of the electron was measured with an accuracy of +0.002 nm . The uncertainty in the momentum of it would be (in $\mathrm{kg} \mathrm{ms}^{-1}$ )

$ \left(h=6.626 \times 10^{-34} \mathrm{Js}\right) $

The number of $d$ electrons in Fe is equal to which of the following?

(i) Total number of ' $s$ ' electrons of Mg .

(ii) Total number of ' $p$ ' electrons of Cl .

(iii) Total number of ' $p$ ' electrons of Ne .

The correct option is

The wavelength associated with the electron moving in the first orbit of hydrogen atom with velocity $2.2 \times 10^6 \mathrm{~ms}^{-1}$ (in nm) is

$\left(m_e=9.0 \times 10^{-31} \mathrm{~kg}, h=6.6 \times 10^{-34} \mathrm{Js}\right)$

The energy required (in eV) to excite an electron of H -atom from the ground state to the third state is

The maximum number of electrons present in an orbital with $n = 4, l = 3$ is

Which quantum number provides information about the shape of an orbital?

If $\Delta x$ is the uncertainty in position and $\Delta v$ is the uncertainty in velocity of a particle are equal, the correct expression for uncertainty in momentum for the same particle is

The number of radial nodes and angular nodes of a $4 f$-orbital are respectively

A subshell $n=3, l=2$ can accommodate maximum of

If the work function for the photoelectron emission of a metal is 3.75 eV, then the threshold wavelength of the radiation needed for the ejection of the electron is approximately

With increasing principal quantum number, the energy difference between adjacent energy levels in $\mathrm{H}$-atom ............ .

The number of protons, neutrons and electrons in $_6^{13}$C respectively are

The masses of an electron, a proton and a neutron respectively will be n the ratio

Match the following species with the correct number of electrons present in them.

Assuming that the incident radiation is capable of ejecting photoelectrons from all the given metals, the lowest kinetic energy of the ejected photoelectron is observed with which of the given metals?

If the energies of two light radiations $E_1$ and $E_2$ are $25 \mathrm{~eV}$ and $100 \mathrm{~eV}$ respectively, then their respective wavelengths $\lambda_1$ and $\lambda_2$ would be in the ratio $\lambda_1: \lambda_2$

If two particles A and B are moving with the same velocity, but wavelength of A is found to be double than that of B. Which of the following statement is correct?

The spectrum of helium is expected to be similar to that of

On the basis of Bohr’s model, the radius of the 3rd orbit is