FSC 1st Year Chemistry 5th Chapter MCQs

Chapter 5: Atomic structure

In this article, the author has explained the most important chemistry MCQs from the fifth chapter( Atomic structure ) of FSC chemistry. All the correct answers have been highlighted in blue color.

1: e/m value for positive rays is found to be maximum for;

a) Hydrogen

b) Oxygen

c) Helium

d) Nitrogen

2: The number of unpaired electrons in an atom with Z=24 at the ground state will be

a) 4

b) 3

c) 5

d) 6

3: The ionization energy of the elements of the 5th group is greater than those of the 6th group. it is because

a) 5^th group element has less electronegativity

b) 5^th group element have half-filled atomic orbitals

c) 6^th group of the elements has a greater shielding effect

d) 5^th group of the elements has a greater shielding effect

4: What is not correct for the sub-shells?

a) They are of different shapes and energies

b) They are arranged in increasing order of increasing values of (n+1)

c) They are arranged in decreasing order of energy as we move away from the nucleus

d) They are represented by azimuthal quantum numbers always

5: when 6d orbital is complete, the entering electron goes into

a) 6f

b) 7s

c) 7p

d) 8s

6: When a neutron decays in a nucleus of an atom

a) Mass number decreases

b) All the above takes place

c) Atom gets a positive charge

d) Increase in the atomic number takes place

7: The total number of electrons present in all the s orbitals, all the p orbitals, and d orbitals of cesium ion are respectively;

a) 6, 26, 10

b) 10, 24, 20

c) 8, 22, 24

d) 12, 20, 23

8: The total number of d-electron present in an atom of atomic number 47 is

a) 10

b) 19

c) 16

d) 20

9: which of the following statement is wholly correct?

a) Electrons of highest energy are those nearest to the nucleus

b) All the electrons in each valence shell are defined by the same principal quantum number

c) px, py, Pz orbitals defined by the same principal quantum number differ very slightly in energy

d) There is a reasonable chance of finding an electron in the nodal region

10: Orbitals having the same energy are called

a) Hybrid orbitals

b) Degenerate orbitals

c) Valence orbitals

d) d-orbitals

11: How many spherical nodes are present in a 4s orbital of a hydrogen atom?

a) 0

b) 4

c) 2

d) 3

12: The number of vacant orbitals in the valence of an atom of an element with z=14 is

a) 1

b) 3

c) 5

d) 6

13: The velocity of a photon is

a) Independent of its wavelength

b) Depends on its source

c) Depends on its wavelength

d) Equal to the square of its wavelength

14: An atom with 8 electrons in its outer shell has a tendency

a) To gain electrons

b) To neither lose or gain electrons

c) To lose electrons

d) Equal to the square of its amplitude

15: Which of the following statements is correct?

a) An orbital describes the path of an electron in an atom

b) An orbital is a region in spaces in which the electron is located

c) An orbital is a function which gives the probability of finding an electron in a given region

d) None is correct

16: The total number of the fundamental particles in one atom of 14C is

a) 6

b) 8

c) 14

d) 20

17: The d-orbital with the orientation along the x and y axes is called

a)dxy

b)dy²

c) dx²

d) dx²y²

18: An atom, with atomic number 14, has a total of

a) 8 p-orbital

b) 4 p-orbital

c) 6 p-orbital

d) 10 p-orbital

19: The nature of the positive rays depends upon

a) The nature of electrons

b) The nature of residual gas

c) The nature of the discharge tube

d) The nature of the electric field

20: Which of the following orbitals are degenerate in multi-electron atoms?

a) 3d orbitals

b) 1s, 2s orbitals

c) 3s, 3p, 3d orbitals

d) 2d orbitals

21: The arrangement of sodium, oxygen, fluorine, and strontium on the basis of increasing first ionization energy

a) Na < Sr < O < F

b) Sr < Na < O < F

c) Sr < Na < F < O

d) Na < Sr < F < O

22: An isotope of ₃₂Ge⁷⁶ is

a) ₃₂Ge⁷⁷

b) ₃₃Ge⁷⁸

c) ₃₄Ge⁷⁷

d) ₃₄Ge⁷⁸

23: A set of isoelectronic species is

a) N₂, CO, CN, O₂²⁺

b) H₂, CO₂, CN, O^–

c) N, H₂S, CO

d) Ca, Mg, Cl

24: The atomic number of an electron ‘M’ is 26. How many electrons are present in the M-shell of the element in the ground state?
a) 11

b) 15

c) 14

d) 16

25: The angular momentum of an electron present in the excited state of Hydrogen is 1.5 h/π. The electron present in its ground state?

a) 3^rd orbit

b) 2^nd orbit

c) 4^th orbit

d) 5^th orbit

26: Which of the following electronic arrangements of the outermost orbit denotes a halogen?

a) 4s² 4p⁶

b) 3s² 3p⁶

c) 5s² 5p⁶

d) Both a and b

27: Which of the following elements has the least number of electrons in its M shell?

a) Sc

b) Mn

c) Ni

d) K

28: The very middle region in between two atomic orbitals is

a) Called nodal region and has a maximum electron density

b) Called nodal region and has a small electron density

c) Called nodal region and has 0 electron density

d) Not called nodal region and has a little electron density

29: The electronic arrangement of a trivalent anion is 2, 8, 8. The atomic number of the element forming this anion is

a) 2

B) 15

c) 18

d) 19

30: What is true for the arrangement of the following sub-shells in an atom?

a) 7s>6p>5d>4f

b) 4f>7s>5d>6p

c) 4f>5d>6p>7s

d) 5d>6p>4f>7s

31: Screening by core electrons in atoms is________?

a) More efficient than that by valence electrons

b) Responsible for a general decrease in atomic radius going down a group

c) Essentially identical to that by valence electrons

d) less efficient than that by valence electrons

32: Which of the following sets contains species that are isoelectronic?

a) Cl, Ar, K

b) F^–, Ne, Na+

c) Al³⁺, S^2-, Ar

d) P^3-, S^2-, Ar

33: The electrons in the 3rd orbit of an atom have______ energy than the electrons in the 2nd orbit

a) More

b) The same

c) Less

d) NONE of these

34: An atom has an atomic weight of W and atomic number N then;

a) Number of electrons = W – N

b) Number of protons = W – N

c) Number of neutrons = W – N

d) Number of neutrons = N

35: Which of the following element outermost orbit’s last electron has magnetic quantum no. m=0?

a) Na

b) O

c) Cl

d) N

36: All the orbitals in a given electron shell (energy level) have the same value of the _____ quantum no. ?

a) Spin

b) Azimuthal

c) Principle

d) Magnetic

37: There are _____ possible values for the magnetic quantum number of an electron in a 5f subshell

a) 7

b) 14

c) 3

d) 5

38: Of the choices below, which gives the order for first ionization energy?

a) S>Si>Cl>Al>Ar

b) Al>Si>S>Cl>Ar

c) Cl>S>Al>Si>Ar

d) Ar>Cl>S>Si>Al

39: _______ have the lowest first ionization energies of the group listed

a) Transition elements

b) Halogens

c) Alkaline earth metals

d) Alkali metals

40: Which of the following has the largest 2nd ionization energy?

a) Na

b) Al

c) Mg

d) P

41: The electron affinity values ( in KJ/mol) of three halogens X, Y, and Z are respectively -349, -333, and -325. Then X, Y, and Z respectively are;

a) F, Cl, and Br

b) Cl, Br, and F

c) Cl, F, and Br

d) Br, Cl, and F

42: The formation of the oxide ion O2- requires first an exothermic and then an endothermic step as shown below

O + e- –> O- ; H₀ = -141 KJ/mol

O^– + e- –> O^2-H₀ = +780 KJ/mol

a) Oxygen is more electronegative

b) Oxygen has a high electron affinity

c) O^– ion will tend to resist the addition of another electron

d) O- ion has a comparatively larger size than Oxygen atom

43: Which of the following has the lowest electron affinity?

a) O

b) N

c) F

d) C

44: No two electrons in the same atom can have an identical set of four quantum numbers. This statement is known as?

a)Hund’s rule

b)Pauli’s Exclusion principle

c)Aufbaus rule

d)(n+1) rule

45:Neutron is a fundamental particle that carries?

a) No charge and mass of one unit

b) No charge and no mass

c) A charge of +1 and mass of 1 unit

d) A charge _1 unit and no mass

46: Principle Quantum number describes?

a) Size of orbital

b) Shape of orbital

c) Orientation of an orbital

d) Spin of orbital

47: Quantum number value for 2p subshell are?

a) n=2, I=1

b) n=1, I=0

c) n=1, I=1

d) n=2, I=0

48: An element has 18 electrons and 20 neutrons. Its charge is +2. What is its mass number?

a) 39

b) 40

c) 32

d) 38

49: Cathode rays are deflected by?

a) Both electric and magnetic field

b) An electric field only

c) Neither electric nor magnetic field

d) A magnetic field only

50: Which of the following statement is wrong about electrons?

a) It has wave-like property

b) It is a particle

c) It emits energy while moving in orbit

d) Its motion is affected by the magnetic field

51: When 6d orbital is complete, the entering electrons go into

a) 7s

b) 7f

c) 7p

d) 7d

52: The heaviest particle among all four given particles is?

a) Proton

b) Meson

c) Electron

d) Neutron

53: The shape of an orbital is governed by?

a) Principle quantum number

b) Spin quantum number

c) Azimuthal quantum number

d) Magnetic quantum number

54: When the azimuthal quantum number (I) is 3 then m can have?

a) 5 values

b) 1 value

c) 7 values

d) 3 value

55: Particle that most affects material properties

a) electrons

b) Protons

c) Neutrons

d) Valence electrons

56: The value of a magnetic quantum number of the last electron Na is?

a) 2

b) -1

c) 0

d) 3

57: A proton has approximately the same mass as

a) An electron

b) An alpha particle

c) A beta particle

d) neutron

58: The absolute charge of an electron is ______?

a) -1.6 x 10^-19 C

b) +1.6 x 10^-19 C

c) 1.6 x 10^-19 C

d) -1

59: Which one of the following sets of the quantum numbers (n, I, m, s) represents an an impossible arrangement?

a) 3, 2, -3, ½

b) 3, 2, -2, ½

c) 4, 0, 0, ½

d) 5, 3, 0, ½

60: Compared to the charge and mass of a proton, an electron has…

a) The same charge and the same mass

b) An opposite charge and the same mass

c) An opposite charge and a similar mass

d) The same charge and the smaller mass