Atomic Structure PYQs Set 9 (PDF)

Set 9 of 12 · Questions 241-270 of 359

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Mere Teacher · Previous Year Questions NEET Chemistry · Atomic Structure · Set 9 (Q241-270)
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241. $In a multi-electron atom, which of the following orbitals described by the three quantum numbers will have the same energy in the absence of magnetic and electric field? (i) n = 1, l = 0, m = 0 (ii) n = 2, l = 0, m = 0 (iii) n = 2, l = 1, m = 1 (iv) n = 3, l = 2, m =1 (v) n = 3, l = 2, m = 0$ (1) $(iv) and (v)$ (2) $(iii) and (iv)$ (3) $(ii) and (iii)$ (4) $(i) and (ii)$ 242. $What is the energy associated with first orbit of Li^{2 +} (R_{H} = 2.18 \times 10^{- 18} J) ?$ (1) $- 19.62 \times 10^{- 18} J$ (2) $- 2.18 \times 10^{- 18} J$ (3) $- 34.88 \times 10^{- 18} J$ (4) $- 8.72 \times 10^{- 18} J$ 243. $Two particles of masses m and 2 m have equal kinetic energies. The de-Broglie wavelengths are in the ratio of$ (1) $1 : 1$ (2) $1 : 2$ (3) $1 : 2$ (4) $2 : 1$ 244. $The electronic configuration for Neodymium is: [Atomic Number for Neodymium 60]$ (1) $[Xe] 4 f^{4} 6 s^{2}$ (2) $[Xe] 5 f^{4} 7 s^{2}$ (3) $[Xe] 4 f^{6} 6 s^{2}$ (4) $[Xe] 4 f^{1} 5 d^{1} 6 s^{2}$ 245. $A photon of wavelength 3000Å strikes a metal surface. The work function of the metal is 2.13 eV . What is the kinetic energy of the emitted photoelectron? (h = 6.626 \times 10^{- 34} Js)$ (1) $4.0 eV$ (2) $3.0 eV$ (3) $2.0 eV$ (4) $1.0 eV$ 246. $A gas absorbs a photon of 355 nm and emits at two wavelengths. If one of the emission is at 680 nm, the other is at:$ (1) $1035 nm$ (2) $325 nm$ (3) $743 nm$ (4) $518 nm$ 247. $Consider the ground state of chromium atom (Z = 24) . How many electrons are with Azimuthal quantum number l = 1 and l = 2 respectively?$ (1) $16 and 5$ (2) $12 and 5$ (3) $12 and 4$ (4) $16 and 4$ 248. $The correct set of four quantum numbers for the valence electron of rubidium atom (Z = 37) is:$ (1) $5, 0, 0, + \frac{1}{2}$ (2) $5, 0, 1, + \frac{1}{2}$ (3) $5, 1, 0, + \frac{1}{2}$ (4) $5, 1, 1, + \frac{1}{2}$ 249. $Which of the following sets of quantum numbers is correct for an electron in 3 d -orbital?$ (1) $n = 3, l = 2, m = - 3, s = + \frac{1}{2}$ (2) $n = 3, l = 3, m = + 3, s = - \frac{1}{2}$ (3) $n = 3, l = 2, m = - 2, s = + \frac{1}{2}$ (4) $n = 3, l = 2, m = - 3, s = - \frac{1}{2}$ 250. $If the kinetic energy of an electron of mass 9.0 \times 10^{- 31} kg is 2.0 \times 10^{- 25} J, the wavelength of the electron in nm is approximately$ (1) $1004.3$ (2) $1204.3$ (3) $1104.3$ (4) $994.3$ 251. $A microscope using appropriate photons is engaged to track an electron in an atom within distance of 0.001 nm . What will be the uncertainty involved in measuring its velocity?$ (1) $5.79 \times 10^{7} m / s$ (2) $5.79 \times 10^{6} m / s$ (3) $4.79 \times 10^{7} m / s$ (4) $3.7 \times 10^{6} m / s$ 252. $The value of work function of a metal X is 3.1 eV . The threshold frequency of it (in Hz) (h = 6.62 \times 10^{- 34} Js)$ (1) $6.49 \times 10^{13}$ (2) $5.49 \times 10^{13}$ (3) $6.49 \times 10^{14}$ (4) $7.49 \times 10^{14}$ 253. $Consider the following sets of quantum numbers : Which of the below setting is not permissible arrangement of electrons in an atom? n l m s$ (1) $4 0 0 - \frac{1}{2}$ (2) $530 + \frac{1}{2}$ (3) $32 -2 - \frac{1}{2}$ (4) $32 -3 + \frac{1}{2}$ 254. $Compare the energies of following sets of quantum numbers for multielectron system. (A) n = 4, 1 = 1 (B) n = 4, 1 = 2 (C) n = 3, 1 = 1 (D) n = 3, 1 = 2 (E) n = 4, 1 = 0 Choose the correct answer from the options given below:$ (1) $(B) > (A) > (C) > (E) > (D)$ (2) $(E) < (C) < (D) < (A) < (B)$ (3) $(E) > (C) > (A) > (D) > (B)$ (4) $(C) < (E) < (D) < (A) < (B)$ 255. $The extra stability of half-filled subshell is due to: (A) Symmetrical distribution of electrons(B) Smaller coulombic repulsion energy(C) The presence of electrons with the same spin in non-degenerate orbitals(D) Larger exchange energy(E) Relatively smaller shielding of electrons by one another Identify the correct statements:$ (1) $(B), (D) and (E) only$ (2) $(A), (B), (D) and (E) only$ (3) $(B), (C) and (D) only$ (4) $(A), (B) and (D) only$ 256. $The de-Broglie wavelength of a tennis ball of mass 60 g moving with a velocity of 10 m/s is approximately (planck’s constant, h = 6.63 \times 1 0^{-34} J-s)$ (1) $1 0^{-33} m$ (2) $1 0^{-31} m$ (3) $1 0^{-16} m$ (4) $1 0^{-25} m$ 257. $The wavelength of the electron in the ground state of hydrogen atom is y Å . What is the wavelength of the electron in the fourth orbit of He^{+} ion (in Å) is$ (1) $2 y$ (2) $3 y$ (3) $y$ (4) $3 y 2$ 258. $The total number of atomic orbitals in fourth energy level of an atom is$ (1) $8$ (2) $16$ (3) $32$ (4) $4$ 259. $In a photoelectric effect experiment the kinetic energy of an emitted electron is 1.986 \times 10^{- 19} J, when a radiation of frequency 1.0 \times 10^{15} s^{- 1} hits the metal. What is the threshold frequency of the metal (in s^{- 1})? (Plank's constant = 6.62 \times 10^{- 34} J s)$ (1) $7.0 \times 10^{14}$ (2) $5.8886 \times 10^{14}$ (3) $7.0 \times 10^{- 15}$ (4) $7.0 \times 10^{15}$ 260. $Which of the following statements are true? (A) The subsidiary quantum number l describes the shape of the orbital occupied by the electron. (B) is the boundary surface diagram of the 2px orbital.(C) The + and - signs in the wave function of the 2px orbital refer to charge.(D) The wave function of 2px orbital is zero everywhere in the xy plane. Choose the correct answer from the options given below:$ (1) $(A) and (B) only$ (2) $(B) and (D) only$ (3) $(C) and (D) only$ (4) $(A), (B) and (C) only$ 261. $Main axis of a diatomic molecule is z, molecular orbital p_{x} and p_{y} overlap to form which of the following orbitals.$ (1) $π molecular orbital$ (2) $0 molecular orbital$ (3) $6 molecular orbitals$ (4) $No bond will form.$ 262. $In hydrogen atom, the de Broglie wavelength of an electron in the second Bohr orbit is [Given that Bohr radius, a_{0} = 52.9 p m]$ (1) $211.6 pm$ (2) $211.6 π pm$ (3) $52.9 π pm$ (4) $105.8 pm$ 263. $The following plot represent the de-Broglie wavelength as a function of the kinetic energy (K.E.) of two particles A and B . Identify the correct relation.$ (1) $m_{A} = m_{B}$ (2) $m_{A} < m_{B}$ (3) $m_{A} > m_{B}$ (4) $m_{A} = m_{B} = 0$ 264. $If uncertainty in position and momentum are equal, then uncertainty in velocity is$ (1) $\frac{1}{m} \frac{h}{π}$ (2) $\frac{h}{π}$ (3) $\frac{1}{2 m} \frac{h}{π}$ (4) $\frac{h}{2 π}$ 265. $The graph between (ψ)^{2} and r (radial distance) is shown below. This represents :$ (1) $3s orbital$ (2) $2s orbital$ (3) $1s orbital$ (4) $2p orbital$ 266. $For hydrogen like species, which of the following graphs provides the most appropriate representation of E vs Z plot for a constant n? [E: Energy of the stationary state, Z: atomic number, n = principal quantum number]$ (1) (2) (3) (4) 267. $The ionization enthalpy of hydrogen atom is 1.312 \times 1 0^{6} J m o l^{-1} . The energy required to excite the electron in the atom from n_{1} = 1 to n_{2} = 2 is$ (1) $8.51 \times 1 0^{5} J m o l^{-1}$ (2) $6.56 \times 1 0^{5} J m o l^{-1}$ (3) $7.56 \times 1 0^{5} J m o l^{-1}$ (4) $9.84 \times 1 0^{5} J m o l^{-1}$ 268. $The orbital angular momentum for an electron revolving in an orbit is given by ℓ (ℓ + 1) \frac{h}{2 π} . This momentum for an s-electron will be given by$ (1) $+ \frac{1}{2} . \frac{h}{2 π}$ (2) $Zero$ (3) $\frac{h}{2 π}$ (4) $2. \frac{h}{2 π}$ 269. $Uncertainty in position of an electron (mass = 9.1 \times 1 0^{- 28} g) moving with a velocity of 3 \times 1 0^{4} c m / s accurate up to 0.001% will be (Use h l_{(} 4_{)} in uncertainty expression where h = 6.626 \times 1 0^{- 27} erg second)$ (1) $5.76 cm$ (2) $7.68 cm$ (3) $1.93 cm$ (4) $3.84 cm$ 270. $Which transition in the hydrogen spectrum would have the same wavelength as the Balmer type transition from n=4 to n = 2 of H e^{+} spectrum$ (1) $n = 2ton= 1$ (2) $n = 1 to n = 3$ (3) $n = 1 to n = 2$ (4) $n = 3 to n = 4$