Thursday, November 21, 2024

MCQ Chemistry Unit 2: Structure of Atom, HS 1st year (with Chapter Summery in Bengali)

 

1. What is the charge of an electron?

a) +1.602 × 10⁻¹⁹ C
b) -1.602 × 10⁻¹⁹ C
c) 0
d) +1

Answer: b) -1.602 × 10⁻¹⁹ C

2. Who proposed the atomic theory that laid the foundation for understanding chemical behavior?

a) J.J. Thomson
b) Ernest Rutherford
c) John Dalton
d) Niels Bohr

Answer: c) John Dalton

3. In the cathode ray experiment, which observation indicates that cathode rays are negatively charged?

a) They travel in straight lines in the absence of an electric field.
b) They are deflected towards the positive plate in an electric field.
c) They produce fluorescence on striking certain materials.
d) They depend on the gas in the tube.

Answer: b) They are deflected towards the positive plate in an electric field.

4. What is the mass of a neutron relative to a proton?

a) Equal to the mass of a proton
b) Slightly greater than the mass of a proton
c) Slightly less than the mass of a proton
d) Half the mass of a proton

Answer: b) Slightly greater than the mass of a proton

5. What does the term "isotopes" refer to?

a) Atoms with the same number of electrons but different chemical properties.
b) Atoms with the same atomic number but different mass numbers.
c) Atoms with different atomic numbers but the same number of neutrons.
d) Atoms that behave identically in all reactions.

Answer: b) Atoms with the same atomic number but different mass numbers.

6. According to Rutherford’s nuclear model, where is the mass of the atom concentrated?

a) Distributed throughout the atom.
b) In the electrons orbiting the nucleus.
c) In the nucleus.
d) In the orbital paths of electrons.

Answer: c) In the nucleus.

7. What is the energy of a photon whose frequency is 5×1014 Hz5 \times 10^{14} \, \text{Hz}? (Planck’s constant h=6.626×10−34 J\cdotpsh = 6.626 \times 10^{-34} \, \text{J·s})

a) 3.313×10−19 J3.313 \times 10^{-19} \, \text{J}
b) 1.986×10−19 J1.986 \times 10^{-19} \, \text{J}
c) 6.626×10−14 J6.626 \times 10^{-14} \, \text{J}
d) 2.312×10−12 J2.312 \times 10^{-12} \, \text{J}

Answer: a) 3.313×10−19 J3.313 \times 10^{-19} \, \text{J}

8. Which postulate is part of Bohr’s model of the hydrogen atom?

a) Electrons move around the nucleus in elliptical orbits.
b) Electrons emit radiation continuously as they orbit the nucleus.
c) The angular momentum of an electron is quantized.
d) Electrons are stationary around the nucleus.

Answer: c) The angular momentum of an electron is quantized.

9. What did Millikan's oil drop experiment determine?

a) Mass of the electron
b) Charge on the electron
c) Charge-to-mass ratio of the electron
d) Size of the electron

Answer: b) Charge on the electron

10. The smallest and lightest positive ion is called:

a) Neutron
b) Proton
c) Electron
d) Photon

Answer: b) Proton

11. What is the value of the Rydberg constant (RHR_H)?

a) 1.097×105 cm−11.097 \times 10^{5} \, \text{cm}^{-1}
b) 2.18×10−18 J2.18 \times 10^{-18} \, \text{J}
c) 6.626×10−34 J\cdotps6.626 \times 10^{-34} \, \text{J·s}
d) 3.0×108 m/s3.0 \times 10^{8} \, \text{m/s}

Answer: a) 1.097×105 cm−11.097 \times 10^{5} \, \text{cm}^{-1}

12. What is the wavelength range of visible light?

a) 200–400 nm
b) 400–750 nm
c) 750–1000 nm
d) 10–400 nm

Answer: b) 400–750 nm

13. Who discovered neutrons?

a) James Chadwick
b) Ernest Rutherford
c) J.J. Thomson
d) Niels Bohr

Answer: a) James Chadwick

14. What does Planck's quantum theory state?

a) Energy can be emitted or absorbed in continuous amounts.
b) Energy is quantized and emitted in discrete packets called quanta.
c) Energy of radiation is independent of its frequency.
d) Energy depends only on the wavelength of radiation.

Answer: b) Energy is quantized and emitted in discrete packets called quanta.

15. Which phenomenon demonstrates the dual nature of light?

a) Photoelectric effect
b) Diffraction
c) Interference
d) Both a and b

Answer: d) Both a and b

16. In the hydrogen spectrum, the series of lines in the visible region is called:

a) Lyman series
b) Balmer series
c) Paschen series
d) Brackett series

Answer: b) Balmer series

17. According to Bohr’s model, what happens when an electron jumps from a higher energy orbit to a lower one?

a) Energy is absorbed.
b) Energy is emitted.
c) Energy remains constant.
d) The atom becomes unstable.

Answer: b) Energy is emitted.

18. What is the angular momentum of an electron in the nn-th orbit as per Bohr’s theory?

a) nh/4πnh/4\pi
b) nh/2πnh/2\pi
c) 2nh/π2nh/\pi
d) nh2/2πnh^2/2\pi

Answer: b) nh/2πnh/2\pi

19. Which particle has a relative charge of +1?

a) Electron
b) Proton
c) Neutron
d) Positron

Answer: b) Proton

20. The dual behavior of matter was proposed by:

a) Max Planck
b) Louis de Broglie
c) Albert Einstein
d) Ernest Rutherford

Answer: b) Louis de Broglie

21. What is the speed of electromagnetic radiation in a vacuum?

a) 3.0×106 m/s3.0 \times 10^{6} \, \text{m/s}
b) 3.0×108 m/s3.0 \times 10^{8} \, \text{m/s}
c) 3.0×1010 m/s3.0 \times 10^{10} \, \text{m/s}
d) 3.0×1012 m/s3.0 \times 10^{12} \, \text{m/s}

Answer: b) 3.0×108 m/s3.0 \times 10^{8} \, \text{m/s}

22. Which of the following series belongs to the ultraviolet region of the hydrogen spectrum?

a) Lyman series
b) Balmer series
c) Paschen series
d) Pfund series

Answer: a) Lyman series

23. What did Rutherford’s alpha-particle scattering experiment conclude?

a) Atoms are indivisible.
b) Atoms have a positively charged nucleus.
c) Electrons revolve in elliptical orbits.
d) All mass is concentrated in electrons.

Answer: b) Atoms have a positively charged nucleus.

24. What type of wave is light?

a) Sound wave
b) Mechanical wave
c) Electromagnetic wave
d) Pressure wave

Answer: c) Electromagnetic wave

25. Which quantum number determines the size of an orbital?

a) Principal quantum number (n)
b) Angular momentum quantum number (l)
c) Magnetic quantum number (m)
d) Spin quantum number (s)

Answer: a) Principal quantum number (n)

26. What is the energy of an electron in the first orbit of hydrogen?

a) 0 J0 \, \text{J}
b) −2.18×10−18 J-2.18 \times 10^{-18} \, \text{J}
c) 2.18×10−18 J2.18 \times 10^{-18} \, \text{J}
d) −1.09×10−18 J-1.09 \times 10^{-18} \, \text{J}

Answer: b) −2.18×10−18 J-2.18 \times 10^{-18} \, \text{J}

27. Which principle explains the distribution of electrons in an atom?

a) Aufbau principle
b) Heisenberg uncertainty principle
c) Hund’s rule
d) Pauli exclusion principle

Answer: a) Aufbau principle

28. Who developed the quantum mechanical model of the atom?

a) Niels Bohr
b) Max Planck
c) Erwin Schrödinger
d) Werner Heisenberg

Answer: c) Erwin Schrödinger

29. Which phenomenon could not be explained by classical physics?

a) Diffraction of light
b) Photoelectric effect
c) Reflection of light
d) Refraction of light

Answer: b) Photoelectric effect

30. What is the unit of frequency in the SI system?

a) Meter (m)
b) Joule (J)
c) Hertz (Hz)
d) Second (s)

Answer: c) Hertz (Hz)

31. Which rule is used to fill orbitals of the same energy before pairing electrons?

a) Aufbau principle
b) Pauli exclusion principle
c) Hund’s rule of maximum multiplicity
d) Uncertainty principle

Answer: c) Hund’s rule of maximum multiplicity

32. The wavelength (λ\lambda) and frequency (ν\nu) of light are related by the equation:

a) c=νλc = \nu \lambda
b) c=ν/λc = \nu / \lambda
c) λ=c/ν2\lambda = c / \nu^2
d) ν=c/λ2\nu = c / \lambda^2

Answer: a) c=νλc = \nu \lambda

33. What does the Pauli exclusion principle state?

a) No two electrons in an atom can have the same set of all four quantum numbers.
b) No two electrons can occupy the same orbital.
c) Orbitals are filled in order of increasing energy.
d) Electrons pair up only after each orbital is singly occupied.

Answer: a) No two electrons in an atom can have the same set of all four quantum numbers.

34. What is the maximum number of electrons in a shell with n=3n = 3?

a) 18
b) 8
c) 10
d) 32

Answer: a) 18

35. Which particle was discovered by J.J. Thomson?

a) Neutron
b) Proton
c) Electron
d) Photon

Answer: c) Electron

36. The charge-to-mass ratio of the electron was determined by:

a) Rutherford
b) Millikan
c) J.J. Thomson
d) Chadwick

Answer: c) J.J. Thomson

37. Which experiment showed that electrons have particle-like properties?

a) Double-slit experiment
b) Oil drop experiment
c) Photoelectric effect
d) Alpha-particle scattering

Answer: c) Photoelectric effect

38. What happens when an electron is in its ground state?

a) It has maximum energy.
b) It is closest to the nucleus.
c) It is at an infinite distance from the nucleus.
d) It emits energy continuously.

Answer: b) It is closest to the nucleus.

39. What is the shape of an s-orbital?

a) Spherical
b) Dumbbell-shaped
c) Cloverleaf
d) Linear

Answer: a) Spherical

40. What is the principle quantum number (nn) for the second orbit of an atom?

a) 0
b) 1
c) 2
d) 3

Answer: c) 2

41. In the hydrogen atom, which series lies in the infrared region?

a) Balmer
b) Lyman
c) Paschen
d) Pfund

Answer: c) Paschen

42. Which fundamental particle has no charge?

a) Electron
b) Proton
c) Neutron
d) Positron

Answer: c) Neutron

43. What does the Heisenberg uncertainty principle state?

a) Electrons have both wave and particle properties.
b) It is impossible to know the exact position and momentum of an electron simultaneously.
c) Energy is quantized in discrete levels.
d) Electrons occupy the lowest energy orbital available.

Answer: b) It is impossible to know the exact position and momentum of an electron simultaneously.

44. What does the Aufbau principle dictate?

a) Electrons enter the orbital with the lowest energy first.
b) No two electrons can have the same quantum numbers.
c) Electrons pair up after single occupancy of orbitals.
d) The probability of finding an electron is highest near the nucleus.

Answer: a) Electrons enter the orbital with the lowest energy first.

45. What are the orbitals in the second energy level?

a) s
b) s and p
c) s, p, and d
d) s, p, d, and f

Answer: b) s and p

১. পরমাণুর গঠন

  • পরমাণুর ধারণা: প্রাচীন ভারতীয় ও গ্রিক দার্শনিকরা (খ্রিষ্টপূর্ব ৪০০) প্রথম পরমাণুর ধারণা দেন। ১৮০৮ সালে জন ডালটন বৈজ্ঞানিক ভিত্তিতে পরমাণু তত্ত্ব উপস্থাপন করেন।
  • পরমাণুর উপাংশিক কণা: ইলেকট্রন, প্রোটন ও নিউট্রনের আবিষ্কার এবং এদের বৈশিষ্ট্য ব্যাখ্যা।

২. পরমাণু মডেল

  • থমসনের মডেল: পরমাণু একটি গোলাকার গঠন, যেখানে ধনাত্মক চার্জ সমভাবে বিতরণ থাকে এবং ঋণাত্মক ইলেকট্রন এতে স্থাপিত।
  • রাদারফোর্ড মডেল: আলফা কণা বিচ্ছুরণের পরীক্ষার মাধ্যমে দেখানো হয় যে পরমাণুর অধিকাংশ স্থান শূন্য, এবং একটি কেন্দ্রীয় নিউক্লিয়াস ধনাত্মক চার্জ বহন করে।
  • বোর মডেল: পরমাণুর ইলেকট্রন নির্দিষ্ট কক্ষপথে ঘোরে, এবং ইলেকট্রন নির্দিষ্ট শক্তি শোষণ বা বিকিরণ করে কক্ষপথ পরিবর্তন করে।

৩. পরমাণু শক্তি স্তর

  • ইলেকট্রনের শক্তি স্তর: বোর মডেল অনুযায়ী, পরমাণুতে ইলেকট্রনের শক্তি স্তর স্থির এবং পরিমাণগত।
  • হাইড্রোজেনের বর্ণালীর ব্যাখ্যা: হাইড্রোজেন পরমাণুর নির্দিষ্ট বর্ণরেখা বোরের তত্ত্বের মাধ্যমে ব্যাখ্যা করা হয়েছে।

৪. ইলেকট্রোম্যাগনেটিক তত্ত্ব

  • ব্ল্যাক বডি রেডিয়েশন: ম্যাক্স প্ল্যাঙ্ক এর কোয়ান্টাম তত্ত্ব।
  • ফটোইলেকট্রিক প্রভাব: আলবার্ট আইনস্টাইনের ব্যাখ্যা অনুযায়ী আলো কণা আকারে (ফোটন) শক্তি বহন করে।
  • দ্বৈত প্রকৃতি: আলো এবং ইলেকট্রনের তরঙ্গ ও কণার প্রকৃতি উভয়ই থাকতে পারে।

৫. কোয়ান্টাম মেকানিক্যাল মডেল

  • ডি-ব্রগ্লি এবং হাইজেনবার্গ তত্ত্ব: ইলেকট্রন তরঙ্গ প্রকৃতি এবং অবস্থান-গতি সম্পর্কিত অনিশ্চয়তার নীতি।
  • অরবিটাল ধারণা: পরমাণুতে ইলেকট্রনের অবস্থান সম্ভাব্যতাভিত্তিক।

৬. পরমাণুর ইলেকট্রনিক কনফিগারেশন

  • আউফবাও নীতি, পাউলি বর্জন নীতি এবং হান্ডের নীতি: ইলেকট্রন কিভাবে অরবিটালে স্থাপিত হয় তা ব্যাখ্যা করা হয়েছে।

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