Chapter 2

For a \(d\)-electron, the orbital angular momentum is (a) \(\sqrt{6}(h / 2 \pi)\) (b) \(\sqrt{2}(h / 2 \pi)\) (c) \((h / 2 \pi)\) (d) \(2(h / 2 \pi)\)

The kinetic energy of an electron in the second Bohr orbit of a hydrogen atom is \(\left[a_{0}\right.\) is Bohr radius] : (a) \(\frac{h^{2}}{4 \pi^{2} m a_{0}^{2}}\) (b) \(\frac{h^{2}}{16 \pi^{2} m a_{0}^{2}}\) (c) \(\frac{h^{2}}{32 \pi^{2} m a_{0}^{2}}\) (d) \(\frac{h^{2}}{64 \pi^{2} m a_{0}^{2}}\)

The orbital angular momentum of an electron in \(2 s\) orbital is: (a) \(+\frac{1}{2} \cdot \frac{h}{2 \pi}\) (b) Zero (c) \(\frac{h}{2 \pi}\) (d) \(\sqrt{2} \cdot \frac{h}{2 \pi}\)

Given that the abundances of isotopes \({ }^{54} \mathrm{Fe},{ }^{56} \mathrm{Fe}\) and \({ }^{\mathrm{s} 7} \mathrm{Fe}\) are \(5 \%, 90 \%\) and \(5 \%\), respectively, the atomic mass of \(\mathrm{Fe}\) is (a) \(55.85\) (b) \(55.95\) (c) \(55.75\) (d) \(56.05\)

A \(3 p\) orbital has : (a) two non spherical nodes (b) two spherical nodes (c) one spherical \& one non spherical node (d) one spherical and two non spherical nodes

The radius of which of the following orbit is same as that of the first Bohr's orbit of hydrogen atom? [20045] (a) \(\mathrm{He}^{+}(n=2)\) (b) \(\mathrm{Li}^{2+}(n=2)\) (c) \(\mathrm{Li}^{2+}(n=3)\) (d) \(\mathrm{Be}^{3+}(n=2)\)

Rurtherford's experiment, which established the nuclear model of the atom, used a beam of (a) \(\beta\)-particles, which impinged on a metal foil and got absorbed (b) \(\gamma\)-rays, which impinged on a metal foil and ejected electrons (c) helium atoms, which impinged on a metal foil and got scattered (d) helium nuclei, which impinged on a metal foil and got scattered

The correct ground state electronic configuration of chromium atom is : (a) \([\mathrm{Ar}] 3 d^{5} 4 s^{1}\) (b) \([\mathrm{Ar}] 3 d^{4} 4 s^{2}\) (c) \([\mathrm{Ar}] 3 d^{6} 4 s^{0}\) (d) \([\mathrm{Ar}] 4 d^{5} 4 s^{1}\)

Which of the following does not characterise X-rays? (a) The radiation can ionise gases (b) It causes \(\mathrm{ZnS}\) to fluorescence (c) Deflected by electric and magnetic fields (d) Have wavelengths shorter than ultraviolet rays

The outermost electronic configuration of the most electronegative element is [1988-1 Mark] (a) \(n s^{2} n p^{3}\) (b) \(n s^{2} n p^{4}\) (c) \(n s^{2} n p^{5}\) (d) \(n s^{2} n p^{6}\)

The wavelength of a spectral line for an electronic transition is inversely related to: (a) the number of electrons undergoing the transition (b) the nuclear charge of the atom (c) the difference in the energy of the energy levels involved in the transition (d) the velocity of the electron undergoing the transition.

The orbital diagram in which the Aufbau principle is violated is: (b) \begin{tabular}{|l|l|l|l|} \cline { 2 - 5 } & \(\uparrow \downarrow\) & \(\uparrow\) & \(\uparrow\) \\ \hline \end{tabular} \begin{tabular}{l|l|l|l|l|} (c) & \(\uparrow \downarrow\) & \(\uparrow\) & \(\uparrow\) & \(\uparrow\) \\ \hline \end{tabular}

The triad of nuclei that is isotonic is (a) \({ }_{6}^{14} \mathrm{C},{ }_{7}^{15} \mathrm{~N},{ }_{9}^{17} \mathrm{~F}\) (b) \({ }_{6}^{12} \mathrm{C},{ }_{7}^{14} \mathrm{~N},{ }_{9}^{19} \mathrm{~F}\) (c) \({ }_{6}{\underline{\phantom{xx}}}^{14} \mathrm{C},{ }_{7}^{14} \mathrm{~N},{ }_{9}^{17} \mathrm{~F}\) (d) \({ }_{6}^{14} \mathrm{C},{ }_{7}^{14} \mathrm{~N},{ }_{9}^{19} \mathrm{~F}\)

The ratio of the energy of a photon of \(2000 \AA\) wavelength radiation to that of \(4000 \AA\) A radiation is : (a) \(1 / 4\) (b) 4 (c) \(1 / 2\) (d) 2

Correct set of four quantum numbers for the valence (outermost) electron of rubidium \((Z=37)\) is : [1984-1 Mark] (a) \(5,0,0,+1 / 2\) (b) \(5,1,0,+1 / 2\) (c) \(5,1,1,+1 / 2\) (d) \(6,0,0,+1 / 2\)

Rutherford's alpha particle scattering experiment eventually led to the conclusion that : (a) mass and energy are related (b) electrons occupy space around the nucleus (c) neutrons are buried deep in the nucleus (d) the point of impact with matter can be precisely determined.

Any \(p\)-orbital can accommodate upto (a) four electrons (b) six electrons (c) two electrons with parallel spins (d) two electrons with opposite spins

Electromagnetic radiation with maximum wavelength is : (a) ultraviolet (b) radiowave (c) \(X\)-ray (d) infrared

The principal quantum number of an atom is related to the (a) size of the orbital (b) spin angular momentum (c) orbital angular momentum (d) orientation of the orbital in space

The radius of an atomic nucleus is of the order of: (a) \(10^{-10} \mathrm{~cm}\) (b) \(10^{-13} \mathrm{~cm}\) (c) \(10^{-15} \mathrm{~cm}\) (d) \(10^{-8} \mathrm{~cm}\)

Bohr model can explain: (a) the spectrum of hydrogen atom only (b) spectrum of an atom or ion containing one electron only (c) the spectrum of hydrogen molecule (d) the solar spectrum

Which electronic level would allow the hydrogen atom to absorb a photon but not to emit a photon? (a) \(3 s\) (b) \(2 p\) (c) \(2 s\) (d) \(1 s\)

The maximum number of electrons that can have principal quantum number, \(n=\) 3, and spin quantum \(m_{s}=-\frac{1}{2}\), is

What is the maximum number of electrons that may be present in all the atomic orbitals with principal quantum number 3 and azimuthal quantum number \(2 ?\)

Rutherford's scattering experiment is related to the size of the (a) nucleus (b) atom (c) electron (d) neutron

Rutherford's experiment on scattering of \(\alpha\)-particles showed for the first time that the atom has (a) electrons (b) protons (c) nucleus (d) neutrons

The \(2 p_{x}, 2 p_{y}\) and \(2 p_{z}\) orbitals of atom have identical shapes but differ in their

The number of neutrons in dipositive zinc ion with mass number 70 is (a) 34 (b) 36 (c) 38 (d) 40

When there are two electrons in the same orbital, they have ............. spins.

The electron density in the \(X Y\) plane in \(3 d_{x^{2}-y^{2}}\) orbital is zero.

The energy of the electron in the \(3 d\)-orbital is less than that in the \(4 s\)-orbital in the hydrogen atom.

Calculate the wave number for the shortest wavelength transition in the Balmer series of atomic hydrogen. $$ \begin{array}{|c|c|c|c|c|c|c|c|c|c|} \hline \text { Metal } & \mathrm{Li} & \mathrm{Na} & \mathrm{K} & \mathrm{Mg} & \mathrm{Cu} & \mathrm{Ag} & \mathrm{l} \mathrm{c} & \mathrm{P}_{1} & \mathrm{~W} \\ \hline \phi(\mathrm{eV}) & 2.4 & 2.3 & 2.2 & 3.7 & 4.8 & 4.3 & 4.7 & 6.3 & 4.75 \\ \hline \end{array} $$

According to Bohr's theory, the electronic energy of hydrogen atom in the \(n^{\text {ti }}\) Bohr's orbit is given \(\operatorname{by} E_{n}=\frac{-21.76 \times 10^{-19}}{n^{2}} \mathrm{~J}\). Calculate the longest wavelength of light that will be needed to remove an electron from the third Bohr orbit of the \(\mathrm{He}^{+}\)ion.

The ground state energy of hydrogen atom is \(-13.6 \mathrm{eV}\). Consider an electronic state \(\psi\) of \(\mathrm{He}^{+}\)whose energy, azimuthal quantum number and magnetic quantum number are \(-3.4 \mathrm{eV}, 2\) and 0 , respectively. Which of the following statement(s) is (are) true from the state \(\psi\) ? (a) It is a \(4 d\) state (b) It has 3 radial nodes (c) It has 2 angular nodes (d) The nuclear charge experienced by the electron in this state is less than \(2 e\), where \(e\) is the magnitude of the electronic charge

Calculate the wavelength in Angstrom of the photon that is emitted when an electron in the Bohr orbit, \(n=2\) returns to the orbit, \(n=1\) in the hydrogen atom. The ionization potential of the ground state hydrogen atom is \(2.17 \times 10^{-11}\) erg per atom.

Ground state electronic configuration of nitrogen atom can be represented by [1999-3 Marks] (a) \(\quad \uparrow \downarrow \mid \uparrow \downarrow \quad \square \uparrow \square\) (c) \(\uparrow \downarrow \prod \downarrow \downarrow\) (d) \(\uparrow \downarrow|\uparrow \downarrow| \downarrow \downarrow \downarrow\)

The energy of the electron in the second and the third Bohr's orbits of the hydrogen atom is \(-5.42 \times 10^{-12}\) erg and \(-2.41 \times 10^{-12}\) erg respectively. Calculate the wavelength of the emitted radiation when the electron drops from the third to the second orbit.

Which of the following satement(s) is (are) correct? [1998 - 2 Marks] (a) The electronic configuration of \(\mathrm{Cr}\) is \([\mathrm{Ar}] 3 \mathrm{~d}^{5} 4 \mathrm{~s}^{\mathrm{I}}\). (Atomic Number of \(\mathrm{Cr}=24)\) (b) The magnetic quantum number may have a negative value. (c) In silver atom, 23 electrons have a spin of one type and 24 of the opposite type. (Atomic Number of Ag \(=47\) ) (d) The oxidation state of nitrogen in \(\mathrm{HN}_{3}\) is \(-3\).

The light radiations with discrete quantities of energy are called .............

Elements of the same mass number but of different atomic numbers are known as ...

Isotopes of an element differ in the number of \(\ldots \ldots \ldots \ldots .\) in their nuclei.

In a given electric field, \(\beta\)-particles are deflected more than \(\alpha\)-particles in spite of \(\alpha\)-particles having larger charge.

According to Bohr's theory, \([2006-6 \mathrm{M}]\) \(E_{n}=\) Total energy, \(K_{n}=\) Kinetic energy, \(V_{n}=\) Potential energy, \(r_{n}=\) Radius of \(n^{\text {th }}\) orbit Match the following: Column I \(\quad\) Column II (A) \(V_{n} / K_{n}=\) ? (p) 0 (B) If radius of \(n^{\text {th }}\) orbit \(\propto E_{n}^{x},(q)-1\) \(x=?\) (C)Angular momentum in(r)-2 lowest orbital (D) (s) 1 \(\frac{1}{r_{n}} \propto Z^{y}, y=?\)

The energy of an electron in the first Bohr orbit of \(\mathrm{H}\) atom is \(-13.6 \mathrm{eV}\). The possible energy value(s) of the excited state(s) for electrons in Bohr orbits of hydrogen is (are) (a) \(-3.4 \mathrm{eV}\) (b) \(-4.2 \mathrm{eV}\) (c) \(-6.8 \mathrm{eV}\) (d) \(-1.5 \mathrm{eV}\)

The sum of the number of neutrons and proton in the isotope of hydrogen is : (a) 6 (b) 2 (c) 4 (d) 3

When alpha particles are sent through a thin metal foil, most of them go straight through the foil because : (a) alpha particles are much heavier than electrons (b) alpha particles are positively charged (c) most part of the atom is empty space (d) alpha particle move with high velocity

Many elements have non-integral atomic masses because: (a) they have isotopes (b) their isotopes have non-integral masses (c) their isotopes have different masses (d) the constitutents, neutrons, protons and electrons, combine to give fractional masses

An isotone of \({ }_{32}^{76} \mathrm{Ge}\) is : (a) \({ }_{32}^{77} \mathrm{Ge}\) (b) \({ }_{33}^{77} \mathrm{As}\) (c) \({ }_{34}^{77} \mathrm{Se}\) (d) \({ }_{34}^{78} \mathrm{Se}\)

Consider the Bohr's model of a one \(-\) electron atom where the electron moves around the nucleus. In the following List-I contains some quantities for the \(n^{\text {h }}\) orbit of the atom and List-II contains options showing how they depend on \(n\) List-I List-II (I) Radius of the \(n^{\text {h }}\) orbit \(\quad\) (P) \(\propto n^{-2}\) (II) Angular momentum of the electron in the \(n^{\text {th }}\) orbit \(\quad(\mathrm{Q}) \propto n^{-1}\) (III) Kinetic energy of the electron in the \(n^{\text {th }}\) orbit \((R) \propto n^{0}\) (IV) Potential energy of the electron in the \(n^{\text {th }}\) orbit \(\quad(\mathrm{S}) \propto n^{1}\) (T) \(\propto n^{2}\) \((\mathrm{U}) \propto n^{1 / 2}\) Which of the following options has the correct ombination considering List-I and List-II? (a) (II), (R) (b) \((\mathrm{II}),(\mathrm{Q})\) (c) (I), (P) (d) (I), (T)

Consider the Bohr's model of a one-electron atom where the electron moves around the nucleus. In the following List-I contains some quantities for the \(n^{\text {w }}\) orbit of the atom and List-II contains options showing how they depend on \(n .\) List-I (I) Radius of the \(n^{\text {th }}\) orbit (II) Angular momentum of the electron in the \(n^{\text {th }}\) orbit (III) Kinetic energy of the electron in the \(n^{\text {t }}\) orbit (IV) Potential energy of the electron in the \(n^{\text {t }}\) orbit List-II (P) \(\propto n^{-2}\) (Q) \(\propto n^{-1}\) (R) \(\propto n^{0}\) \((\mathrm{S}) \propto n^{1}\) (T) \(\propto n^{2}\) \((\mathrm{U}) \propto n^{1 / 2}\) Which of the following options has the correct combination considering List-I and List-II? (a) (III), (S) (b) (IV), (Q) (c) (III), (P) (d) (IV), (U)