Atomic Structure · JEE Main previous year questions

If the de Broglie wavelength of the electron in $n^{th}$ Bohr orbit in a hydrogenic atom is equal to $1.5\pi a_0$ ($a_0$ is Bohr radius), then the value of n/z is -

1. A.0.75
2. B.0.40
3. C.1.50
4. D.1.0

The correct option with respect to the Pauling electronegativity values of the element is :

1. A.Ga < Ge
2. B.Si < Al
3. C.Te > Se
4. D.P > S

The de Broglie wavelength $(\lambda )$ associated with a photoelectron varies with the frequency $(\nu )$ of the incident radiation as, [${\nu }_0$ is threshold frequency] :

1. A.$\lambda \propto \frac{1}{(\nu -{\nu }_0{)}^{\frac{3}{2}}}$
2. B.$\lambda \propto \frac{1}{(\nu -{\nu }_0{)}^{\frac{1}{4}}}$
3. C.$\lambda \propto \frac{1}{(\nu -{\nu }_0)}$
4. D.$\lambda \propto \frac{1}{(\nu -{\nu }_0{)}^{\frac{1}{2}}}$

According to molecular orbital theory, which of the following is true with respect to $\mathrm{L}{\mathrm{i}}_2^{+}$ and $\mathrm{L}{\mathrm{i}}_2^{-}$ ?

1. A.$\mathrm{L}{\mathrm{i}}_2^{+}$ is unstable and $\mathrm{L}{\mathrm{i}}_2^{-}$ is stable
2. B.$\mathrm{L}{\mathrm{i}}_2^{+}$ is stable and $\mathrm{L}{\mathrm{i}}_2^{-}$ unstable
3. C.Both are stable
4. D.Both are unstable

For emission line of atomic hydrogen from $n_i=8$ to $n_f=n$, the plot of wave number $(\bar{\nu })$ against $\left(\frac{1}{n^2}\right)$ will be (The Rydberg constant, ${\mathrm{R}}_{\mathrm{H}}$ is in wave number unit)

1. A.Linear with intercept $-{\mathrm{R}}_{\mathrm{H}}$
2. B.Non linear
3. C.Linear with slope ${\mathrm{R}}_{\mathrm{H}}$
4. D.Linear with slope $-{\mathrm{R}}_{\mathrm{H}}$

Ejection of the photoelectron from metal in the photoelectric experiment can be stopped by applying 0.5 V when the radiation of 250 nm is used. The work function of the metal is :

1. A.4 eV
2. B.4.5 eV
3. C.5 eV
4. D.5.5 eV

In the molecular orbital diagram for the molecular ion, ${\text{N}}_2^{+}$, the number of electrons in the ${\sigma }_{2{\text{p}}_z}$ molecular orbital is :

1. A.0
2. B.1
3. C.2
4. D.3

In graphite and diamond, the percentage of p-characters of the hybrid orbitals in hybridisation are respectively :

1. A.33 and 25
2. B.33 and 75
3. C.50 and 75
4. D.67 and 75

According to molecular orbital theory, which of the following will not be a viable molecule?

1. A.${\text{He}}_2^{2+}$
2. B.${\text{He}}_2^{+}$
3. C.${\text{H}}_2^{-}$
4. D.${\text{H}}_2^{2-}$

The electron in the hydrogen atom undergoes transition from higher orbitals to orbital of radius 211.6 pm. This transition is associated with :

1. A.Lyman series
2. B.Balmer series
3. C.Paschen series
4. D.Brackett series

The electronic configuration with the highest ionization enthalpy is :

1. A.$[\mathrm{Ne}]3{\mathrm{s}}^{2}3{\mathrm{p}}^1$
2. B.$[\mathrm{Ne}]3{\mathrm{s}}^{2}3{\mathrm{p}}^2$
3. C.$[\mathrm{Ne}]3{\mathrm{s}}^{2}3{\mathrm{p}}^3$
4. D.$[\mathrm{Ar}]3{\mathrm{d}}^{10}4{\mathrm{s}}^{2}4{\mathrm{p}}^3$

The correct set of four quantum numbers for the valence electrons of rubidium atom (Z= 37) is:

1. A.5, 1, 1, + 1/2
2. B.5, 1, 0, + 1/2
3. C.5, 0, 0, + 1/2
4. D.5, 0, 1, + 1/2

The following sets of quantum numbers represent four electrons in an atom. (i) $n=4,l=1$ (ii) $n=4,l=0$ (iii) $n=3,l=2$ (iv) $n=3,l=1$ The sequence representing increasing order of energy, is

1. A.(iii) < (i) < (iv) < (ii)
2. B.(iv) < (ii) < (iii) < (i)
3. C.(i) < (iii) < (ii) < (iv)
4. D.(ii) < (iv) < (i) < (iii)

If the radius of first orbit of H atom is $a_0$, the de Broglie wavelength of an electron in the third orbit is

1. A.$4\pi a_0$
2. B.$8\pi a_0$
3. C.$6\pi a_0$
4. D.$2\pi a_0$

The limiting line in Balmer series will have a frequency of (Rydberg constant, $R_{\infty }=3.29\times 10^{15}cycles/s$)

1. A.$8.22\times 10^{14}{\mathrm{s}}^{-1}$
2. B.$3.29\times 10^{15}{\mathrm{s}}^{-1}$
3. C.$3.65\times 10^{14}{\mathrm{s}}^{-1}$
4. D.$5.26\times 10^{13}{\mathrm{s}}^{-1}$

According to Bohr's theory, the angular momentum of an electron in $5^{\mathrm{th}}$ orbit is

1. A.$10h/\pi$
2. B.$2.5h/\pi$
3. C.$25h/\pi$
4. D.$1.0h/\pi$

Uncertainty in the position of an electron ($\mathrm{mass}=9.1\times 10^{-31}\mathrm{kg}$) moving with a velocity $300\mathrm{m}{\mathrm{s}}^{-1}$, accurate up to $0.001\%$ will be ($h=6.63\times 10^{-34}\mathrm{Js}$)

1. A.$1.92\times 10^{-2}\mathrm{m}$
2. B.$3.84\times 10^{-2}\mathrm{m}$
3. C.$19.2\times 10^{-2}\mathrm{m}$
4. D.$5.76\times 10^{-2}\mathrm{m}$

The “spin-only” magnetic moment [in units of Bohr magneton, (${\mu }_{\mathrm{B}}$)] of $\mathrm{N}{\mathrm{i}}^{2+}$ in aqueous solution would be : (Atomic number of Ni = 28)

1. A.$2.84$
2. B.$4.90$
3. C.$0$
4. D.$1.73$

In a multi-electron atom, which of the following orbitals described by the three quantum numbers will have the same energy in the absence of magnetic and electric fields? (A) n = 1, l = 0, m = 0 (B) n = 2, l = 0, m = 0 (C) n = 2, l = 1, m = 1 (D) n = 3, l = 2, m = 1 (E) n = 3, l = 2, m = 0

1. A.(D) and (E)
2. B.(C) and (D)
3. C.(B) and (C)
4. D.(A) and (B)

The photon of hard gamma radiation knocks a proton out of ${}_{12}^{24}\mathrm{Mg}$ nucleus to form

1. A.the isotope of parent nucleus
2. B.the isobar of parent nucleus
3. C.the nuclide ${}_{11}^{23}\mathrm{Na}$
4. D.the isobar of ${}_{11}^{23}\mathrm{Na}$

Which of the following sets of quantum numbers is correct for an electron in 4f orbital?

1. A.n = 4, l = 3, m = +1, s = + 1/2
2. B.n = 4, l = 4, m = -4, s = - 1/2
3. C.n = 4, l = 3, m = +4, s = + 1/2
4. D.n = 3, l = 2, m = -2, s = + 1/2

Consider the ground state of Cr atom (Z = 24). The number of electrons with the azimuthal quantum numbers, l = 1 and 2 are respectively

1. A.16 and 4
2. B.12 and 5
3. C.12 and 4
4. D.16 and 5

The wavelength of the radiation emitted when in a hydrogen atom electron falls from infinity to stationary state 1, would be (Rydberg constant = $1.097\times 10^7{\mathrm{m}}^{-1}$)

1. A.406 nm
2. B.192 nm
3. C.91 nm
4. D.$9.1\times 10^{-8}$ nm

Which one of the following complexes is an outer orbital complex?

1. A.$[\mathrm{Fe}(\mathrm{CN}{)}_6{]}^{4-}$
2. B.$[\mathrm{Ni}(\mathrm{N}{\mathrm{H}}_3{)}_6{]}^{2+}$
3. C.$[\mathrm{Co}(\mathrm{N}{\mathrm{H}}_3{)}_6{]}^{3+}$
4. D.$[\mathrm{Mn}(\mathrm{CN}{)}_6{]}^{4-}$

Of the following outer electronic configurations of atoms, the highest oxidation state is achieved by which one of them?

1. A.$(n-1)d^{3}n{s}^2$
2. B.$(n-1)d^{5}n{s}^1$
3. C.$(n-1)d^{8}n{s}^2$
4. D.$(n-1)d^{5}n{s}^2$