Atomic Structure

1. The probability of finding the electron in the nucleus is?

  1. 100% due to forces of attraction
  2. finite for all orbitals
  3. Zero for all orbitals
  4. Zero for some orbitals and finite for others

Explanation

An electron orbital is most commonly defined as the radius of the sphere that encloses 95 % of the total electron probability and the probability of finding an electron in an orbital is approximately 95%.

Video Explanation

2. When an electron is brought from infinite distance close to the nucleus of the atom, the energy of Electron-nucleus system?

  1. decreases to a smaller positive value
  2. increases to a greater positive value
  3. increases to a greater negative value
  4. decreases to a greater negative value

Explanation

The energy of an electron is considered as zero at infinite distance from the nucleus as electron come nearer it gets bounded from the nucleus so the energy is negative. Energy is inversely proportional to the distance so, as the distance decreases energy increases to a greater negative value.

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3. Who proposed the atomic theory first??

  1. Dalton
  2. JJ Thomson
  3. Neils Bohar
  4. Millikan

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4. When an atom absorbs energy the lines in the spectrum will appear which are?

  1. Brighter
  2. Darker
  3. Colourless
  4. none of these

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5. when an electron is moving with velocity of 2.188*10 6 ms-1 in first orbit of bohr atomic model of hydrogen. what is de Broglie wavelength of electron?

  1. 0.33 nm
  2. o.34nm
  3. o.35nm
  4. 0.36 nm

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6. According to De broglie , if velocity of particle is infinite then its wavelength will be?

  1. small
  2. large
  3. zero
  4. none of these

Explanation

According to de Broglie’s hypothesis, then the wavelength would become infinite as the momentum is zero

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7.  Hybridization of Nitrogen in Pyridine?

  1. sp3
  2. sp
  3. not Hybridized
  4. none of these

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8. The orientation of atomic orbitals depends on their?

  1. Spin quantum number
  2. Magnetic quantum number
  3. azimuthal quantum number
  4. principal quantum number

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9. The type of hybridization of boron in diborane is?

  1. sp3d2
  2. sp3
  3. sp2
  4. sp

video Explanation

10.The electronic configuration of atomic number 20 of an atom is which of the following??

  1. 2,6,6,2
  2. 2,8,8,2
  3. 2,4,6,1
  4. none of these

Video Explanation

11. Hybridization of sulphur in sulphuric acid?

  1. sp
  2. sp2
  3. d2sp3
  4. sp3

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12. What happens to the atomic number during a chemical reaction??

  1. It increases
  2. Remains the same
  3. Changes alternatively
  4. None of these

Video Explanation

13.Which of the following properties of atom could be explained correctly by Thomson Model of atom??

  1. Overall neutrality of atom
  2. Spectra of hydrogen atom
  3. Position of electrons, protons and neutrons in atom
  4. Stability of atom

Explanation

Stability of atom: Only overall neutrality of an atom could be explained correctly by Thomson model of atom.

Thomson Atomic Model – Plum pudding model, Postulates  an atom is made up of a positively charged sphere into which negatively charged electrons are implanted.

Video Explanation

14. Which of the following statements about the electron is incorrect??

  1. It is a negatively charged particle
  2. It is a basic constituent of all atoms
  3. The mass of electron is equal to the mass of neutron
  4. all of these

Video Explanation

15. What is shape of tri iodine??

  1. v shaped
  2. angular
  3. trigonal
  4. linear

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16. Which of the following conclusions could not be derived from Rutherford’s α -particle scattering experiment?

  1. Most of the space in the atom is empty
  2. The radius of the atom is about 10–10 m while that of nucleus is 10–15 m
  3. Electrons move in a circular path of fixed energy called orbits
  4. Electrons and the nucleus are held together by electrostatic forces of attraction

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17. Maximum number of electrons in a subshell with l = 3 and n = 4 is?

  1. 16
  2. 14
  3. 12
  4. 10

Video Explanation

18. The correct set of four quantum numbers for the valence electron of rubidium atom (Z = 37) is?

  1. 5, 0, 1, + 1/2
  2. 5, 1, 0, + 1/2
  3. 5, 1, 1, + 1/2
  4. 5, 0, 0, + 1/2

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19. Mg2+ is isoelectronic with………..?

  1. Ca2+
  2. Na+
  3. Zn2+
  4. Cu2+

Video Explanation

20. Electronic configuration of the outer shell of the element Gd with atomic number 64 is?

  1. 4f4 5d5 6s1
  2. 4f3 5d5 6s2
  3. 4f5 5d4 6s1
  4. 4f7 5d1 6s2

Video Explanation

Chemistry for PPSC FPSC BPSC SPSC KPSC NTS Lecturer Educator Exam |Test Data |Mcqs Best Explanation | Chemistry MCQs

Course Code: #expxch001 for Chemistry Complete Assessment course

Topic Code #expch_001 Atomic Structure

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