CBSE Class 11 Chemistry Structure of Atom Assignment

Structure Of Atom MCQ Questions with Answers Class 11 Chemistry

Question- What is the ratio of mass of an electron to the mass of a proton?

(a) 1 : 2

(b) 1 : 1

(c) 1 : 1837

(d) 1 : 3

Answer-(c)

Question- The velocity of particle A is 0.1 ms^–1 and that of particle B is 0.05 ms^–1. If the mass of particle B is five times that of particle A, then the ratio of de-Broglie wavelengths associated with the particles A and B is

(a) 2 : 5

(b) 3 : 4

(c) 6 : 4

(d) 5 : 2

Answer-(d)

Question-Arrange the following elements in the order of ease of detection of wave properties, in the de Broglie experiment. H, Li, Be, B, K

(a) H < Be, B < Li < K.

(b) H > Li > K > Be > B

(c) H > Li > Be > B > K

(d) H < Li < Be < B < K

Answer-(c)

Question-In which of the following the amount of deviation from their path in the presence of electric and magnetic field will be maximum?

(a) N^2–

(b) N^3–

(c) N^–

(d) N

Answer-(b)

Question-The Bohr orbit radius for the hydrogen atom (n = 1) is approximately 0.530 Å. The radius for the first excited state (n = 2) orbit is (in Å)

(a) 0.13

(b) 1.06

(c) 4.77

(d) 2.12

Answer-(d)

Question-Which of the following pairs have identical values of e/m?

(a) A proton and a neutron

(b) A proton and deuterium

(c) Deuterium and an α-particle

(d) An electron and γ-rays

Answer-(c)

Question-If the alpha-particles are projected against the following atoms Fe, Be, Mg, Al then increasing order in which the alpha-particle feel repulsion will be

(a) Be, Mg, Al, Fe

(b) Be, Al, Mg, Fe

(c) Mg, Al, Mg, Fe

(d) Al, Mg, Fe, Be

Answer-(a)

Question-Chlorine exists in two isotopic forms, C1-37 and C1-35 but its atomic mass is 35.5. This indicates the ratio of C1-37 and C1-35 is approximately

(a) 1 : 2

(b) 1 : 1

(c) 1 : 3

(d) 3 : 1

Answer-(c)

Question-According to Bohr’s theory the energy required for an electron in the Li²⁺ ion to be emitted from n = 2 state is (given that the ground state ionization energy of hydrogen atom is 13.6 eV)

(a) 61.2 eV

(b) 13.6 eV

(c) 30.6 eV

(d) 10.2 eV

Answer-(c)

Question-The increasing order for the values of e/m (charge/mass) is

(a) e, p, n, α

(b) n, p, e, α

(c) n, p, α, e

(d) n, α, p, e

Answer-(d)

Question-The ratio between kinetic energy and the total energy of the electrons of hydrogen atom according to Bohr’s model is

(a) 2 : 1

(b) 1 : 1

(c) 1 : – 1

(d) 1 : 2

Answer-(c)

Question- In hydrogen atomic spectrum, a series limit is found at 12186.3 cm^–1. Then it belong to

(a) Lyman series

(b) Balmer series

(c) Paschen series

(d) Brackett series

Answer-(c)

Question-The deflection of the particles from their path in presence of electric and magnetic field will be maximum in which of the following.

(a) O

(b) N

(c) U

(d) He

Answer-(d)

Question- Which transition in the hydrogen atomic spectrum will have the same wavelength as the transition, n = 4 to n = 2 of He⁺ spectrum?

(a) n = 4 to n = 3

(b) n = 3 to n = 2

(c) n = 4 to n = 2

(d) n = 2 to n = 1

Answer-(d)

Question-Two fast moving particles X and Y are associated with de Broglie wavelengths 1 nm and 4 nm respectively. If mass of X in nine times the mass of Y, the ratio of kinetic energies of X and Y would be

(a) 3 : 1

(b) 9 : 1

(c) 5 : 12

(d) 16 : 9

Answer-(d)

More Question

ONE MARK QUESTIONS

1. State Heisenberg’s uncertainty principle.

2. What is meant by “ Energy of an electron in a hydrogen atom is quantized”?

3. Explain the dual nature of light.

4. Why is the concept of orbit replaced by the concept of orbital?

5. State (n+l) rule.

6. Give reason: In the building up of atoms, 4s is filled before 3d

7. Why are half filled and completely filled orbitals more stable?

8. Electronic configuration in Copper is [Ar] 4s¹, 3d¹⁰ and not [Ar] 4s², 3d⁹

9. With the help of Pauli’s exclusion principle and the concept of atomic numbers for orbitals, show that an M shell cannot accommodate more than 18 electrons.

10. Draw the shapes (boundary surfaces) of the following orbitals.

(i) 2p_y (ii) 3d_x² _{– y}²

TWO MARKS QUESTIONS

1. Define

i) Photoelectric effect

ii) Black body radiation

2. Differentiate

i) Absorption and Emission spectrum

ii) Orbit and orbital

3. Which is more stable i) Mn2+ or Mn3+ii) Fe2+ or Fe3+? Give reason.

4. Among the following pairs of orbitals which orbital will experience the larger effective nuclear charge? (i) 2s and 3s, (ii) 4d and 4f, (iii) 3d and 3p.

5. Based on Bohr Bury rules arrange the following orbital’s in the increasing order of energy.
(i) 5f , 4d , 7s , 7p (ii) 5p , 4d , 5d , 4f , 6s

6. Discuss the similarities and differences (two each) between a 1s and a 2s orbital.

7. a) How many electrons in an atom may have the following quantum number?
(i) n = 4 ms = +1/2 (ii) n = 3 , l = 0
b) What are the atomic numbers of elements whose outermost electrons are represented by
(i) 3s¹ (ii) 2p³ (iii) 3d⁶

8. What are the possible values of l and m for a) n=3 b) n=2

9. List the quantum numbers of
a) unpaired electrons in F , Ni2+ b) valence electrons in P , Ca

10. Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 6800Ao.Calculate the threshold frequency and work function of the metal.

11. The speed of an electron moving at 600m/s is measured to an accuracy of 0.005%. What would be the minimum error in determining its position?

12. Calculate the uncertainty in the velocity of a cricket ball if the mass is 150g. Uncertainty in the position is 1 angstrom.

THREE MARKS QUESTIONS

1. i) When would the wavelength associated with an electron be equal to the wavelength associated with a proton?
ii) Two particles A and B are in motion. If the momentum of A is half of that of B and if the wavelength of A is 4.5 x 10² nm, what is the wavelength of B?

2. i) Show that the wavelength related to a 250g ball moving with a speed of 100 m/s is too short to be observed.
ii) Calculate the speed of an electron if its de Broglie wavelength is twice its displacement in one second.

3. A photon of wavelength 4 × 10^–7 m strikes on metal surface, the work function of the metal being 2.13 eV. Calculate
(i) the energy of the photon (eV),
(ii) the kinetic energy of the emission, and
(iii) the velocity of the photoelectron (1 eV = 1.6020 × 10^–19J).

4. Calculate the energy absorbed, frequency and wavelength when an electron with energy
217.9 x 10^-21 J jumps to an energy level with energy 544.8 x 10^-20J.

5. Calculate the energy and radius of the first orbit of He⁺ ion.

Question. 1. The electronic configuration of the element with atomic number 19 is
(a) 2,8,7
(b) 2,9,8
(c) 2,8,8,1
(d) 2,10,7
Answer: C

Question. 2. The valence electrons of an element are responsible for
(a) Physical properties of an element
(b) Chemical properties of an element
(c) Both the properties
(d) None of these
Answer: B

Question. 3. An element has electronic configuration 2,8,4 it will be classified as
(a) Metal
(b) Non metal
(c) Metalloid
(d) None of these
Answer: C

Question. 4. Isotopes of an element do not have
(a) Same number of element
(b) Same physical properties
(c) Same chemical properties
(d) Same electrical charge on the nucleus
Answer: B

Question. 5. Amongst element X (2,8,6) and (2,8,8) which is more reactive and why ?
(a) X because it is a metal
(b) Y because it is non metal
(c) X because it has 6 valence electrons
(d) Y because it is gas
Answer: C

Question. 6. Cathode rays have
(a) Mass only
(b) Charge only
(c) Both mass and charge
(d) Neither mass nor charge
Answer: C

Question. 7. Which of these is a pair of isobars ?
(a) \( {}_6\text{C}^{12}, {}_8\text{O}^{16} \)
(b) \( {}_6\text{C}^{13}, {}_6\text{C}^{14} \)
(c) \( {}_{20}\text{Ca}^{40}, {}_{18}\text{Ar}^{40} \)
(d) None of these
Answer: C

Question. 8. \( {}_7\text{N}^{15} \) and \( {}_8\text{O}^{16} \) are a pair of
(a) Isotopes
(b) Isobars
(c) Isotones
(d) None of these
Answer: C

Question. 9. The nucleus of the hydrogen atom is called as
(a) Neutron
(b) Electron
(c) Proton
(d) Nucleons
Answer: C

Question. 10. The \( e/m \) value for cathode rays
(a) varies with the nature of the gas
(b) does not vary with the nature of gas
(c) could not be determined by J.J. Thomson
(d) Both (b) & (c) are correct
Answer: B

Question. 11. Cathode rays get deflected in an electric field towards
(a) Positive plate
(b) Negative Plate
(c) No deflection takes place
(d) First towards negative plate and then towards positive plate
Answer: A

Question. 12. Isotopes differ in
(a) No. of electrons
(b) No. of protons
(c) No. of neutrons
(d) Chemical reactivity
Answer: C

Question. 13. The atomic number of an element ‘y’ is 20. The electronic configuration of the ion having inert gas configuration is
(a) 2,8,10
(b) 2,18
(c) 2,10,8
(d) 2,8,8
Answer: D

Question. 14. Which amongst the following statement is true?
(a) \( \alpha \) rays are cathode rays
(b) Electrons make up the cathode rays
(c) Protons make up the cathode rays
(d) Electromagnetic radiation make up the cathode rays
Answer: B

Question. 15. The isotope of hydrogen that contains the same number of protons and neutrons in its nucleus is called
(a) Protium
(b) Deuterium
(c) Tritium
(d) None of these
Answer: B

Question. 16. \( \alpha \) particle is emitted by \( {}_{92}\text{X}^{238} \) during radioactivity. The new specie y should be :
(a) \( {}_{90}\text{Y}^{234} \)
(b) \( {}_{90}\text{Y}^{238} \)
(c) \( {}_{92}\text{Y}^{234} \)
(d) \( {}_{94}\text{Y}^{234} \)
Answer: A

Question. 17. When an \( \alpha \)-particle is emitted
(a) Element moves 2 places to the right in the periodic table
(b) Element moves one place to the left
(c) Element moves 2 places to the left in the periodic table
(d) Element maintains its position
Answer: C

Question. 18. If the nuclide of actinium \( {}_{89}\text{Ac}^{228} \), emits \( \beta \) particle, the daughter nuclide will be
(a) \( {}_{88}\text{Ra}^{228} \)
(b) \( {}_{90}\text{Th}^{228} \)
(c) \( {}_{87}\text{Fr}^{224} \)
(d) \( {}_{90}\text{Th}^{229} \)
Answer: B

Question. 19. The relative atomic masses of many elements are not whole numbers because
(a) They can’t be determined very accurately
(b) The atoms ionize during the determination
(c) of the existence of isotopes
(d) of the presence of impurities
Answer: C