Free Atomic Structure MCQs with Answers
922 Atomic Structure MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Atomic structure covers the discovery of the proton, Planck's quantum theory, hydrogen emission spectra and the evidence for quantized energy levels. You will use quantum numbers to describe orbitals, distinguish s, p, d and f orbital shapes, and write electronic configurations, including the correct order of electron filling.
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922 questions · page 15 of 47
- A. Decrease
- B. Increase
- C. Remain the same
- D. May or may not remain the same
Explanation: As the principal quantum number (n) increases, the size of the s-orbitals also increases.
Correct answer: Increase- A. Oxygen (O)
- B. Boron (B)
- C. Carbon (C)
- D. Sodium (Na)
Explanation: Oxygen has 8 electrons. After losing 1 electron, it will have 7 electrons which is the same as nitrogen. So, option A is correct.
Correct answer: Oxygen (O)- A. They are spherical
- B. They have a strong directional character
- C. They are tetra lobed
- D. They form ionic bond only
Explanation: The shape of a p-orbital is such that it is concentrated in two lobes that are oriented in opposite directions.
Correct answer: They have a strong directional character- A. 1p
- B. 5d
- C. 7f
- D. 1s
Explanation: The "1p" sub-shell does not exist. In electron configuration notation, sub-shells are represented by a combination of numbers and letters.
Correct answer: 1p- A. 4
- B. 5
- C. 6
- D. 7
Explanation: Chromium (Cr) has 6 unpaired electrons. Its electronic configuration is: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹ In the 3d orbital, there are 5…
Correct answer: 6- A. Increases by 33%
- B. Decreases by 66%
- C. Increases by 66%
- D. Decreases by 33%
Explanation: We know that v can be expressed as: v = c/λ₁. Where v is the frequency, c is the speed of light and λ is the wavelength.
Correct answer: Decreases by 66%- A. Px
- B. dz2
- C. s
- D. f
Explanation: The orbital with a shape of a dumbbell with a doughnut is called a d-orbital.
Correct answer: dz2- A. Becomes half
- B. Becomes double
- C. Remains unchange
- D. Becomes one fourth
Explanation: The Rydberg's constant is a physical constant that is related to the energy levels of electrons in atoms.
Correct answer: Becomes half- A. Se
- B. Sr
- C. Zr
- D. Mo
Explanation: The electronic configuration of Zirconium (Zr), which has an atomic number of 40, is: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d².
Correct answer: Zr- A. 17
- B. 3
- C. 18
- D. 8
Explanation: A chloride ion (Cl-) is formed when a chlorine atom (Cl) gains one extra electron to achieve a stable electronic configuration.
Correct answer: 8- A. Copper
- B. Iron
- C. Nickel
- D. Chromium
Explanation: The electron configuration of chromium is 1s2 2s2 2p6 3s2 3p6 4s1 3d5. In the ground state, chromium has 13 electrons in its M-shell (3s2…
Correct answer: Chromium- A. Energy of electron when n=0
- B. The energy of electron in the atom is lower than the energy of a free electron in motion
- C. The energy of electron in the atom is lower than the energy of a free electron at rest
- D. The energy of electron decease as it moves away from nucleus
Explanation: The energy of an electron in the atom is lower than the energy of a free electron at rest which is taken as zero.
Correct answer: The energy of electron in the atom is lower than the energy of a free electron at rest- A. 100% due to the forces of attraction
- B. Zero for all elements
- C. Finite for all elements
- D. Zero for some elements and finite for others
Explanation: The probability of finding an electron in the nucleus is zero. An orbital represents the region around the nucleus, where the probability…
Correct answer: Zero for all elements- A. y/3
- B. 3y
- C. y
- D. 9y
Explanation: Radius of nth orbit of an electron is given by: rn = yn2/z . For hydrogen atom, z = 1 rn = yn2 For third orbit, n = 3 Thus radius of third…
Correct answer: 9y- A. Oxygen
- B. Nitrogen
- C. Methane
- D. Carbon monoxide
Explanation: To determine the gas with the smallest e/m (charge-to-mass) value when producing positive rays, we can calculate the e/m values by…
Correct answer: Carbon monoxide- A. Na+1 is smaller in size as compared to Mg+2
- B. Sodium has lost its valence shell while Mg hasn't
- C. Both have 10 electrons
- D. Both have 11 and 12 electrons respectively
Explanation: Na+ = 11 - 1 = 10 Mg+2 = 12 - 2 = 10 Hence both have 10 electrons.
Correct answer: Both have 10 electrons- A. 1
- B. 0
- C. 4
- D. 9
Explanation: Bromine belongs to group 7A and has the electronic configuration :[Kr]5s2,4d10,5px2,5py2,5pz1 .The electronic configuration shows that…
Correct answer: 1- A. Na
- B. N
- C. S
- D. Be
Explanation: 3 unpaired e-s in oxygen makes it the atom with the most no. of free electrons among all the other options,so it is the correct option.
Correct answer: S- A. 3
- B. 4
- C. 6
- D. 5
Explanation: Ion is formed by either gaining or losing an electron.The positive sign indicates the losing of an electron.The ion X+2 shows that the ion…
Correct answer: 4- A. [Ar]4S23d9
- B. [Ar]4S13d10
- C. [Ar]4S24p63d3
- D. [Ar]4S14d9
Explanation: The correct electron configuration for copper (Cu) with atomic number 29 is:b.
Correct answer: [Ar]4S13d10