All Free Chemistry MCQs with Answers

• A. Aufbau principle
• B. Pauli's exclusion principle
• C. Hund's rule
• D. Le Chatelier's principle

Explanation: Correct option is C. Thus, nitrogen contains three unpaired electrons following Hund's rule of maximum multiplic According to this rule…

• A. n
• B. m
• C. s
• D. I

Explanation: The shape of an orbital is described by the azimuthal quantum number or orbital angular momentum quantum number (l).

• A. A
• B. B
• C. C
• D. D

Explanation: Option 'B' is correct because the image shown in it is not violating any rule and shows the correct visual representation of the…

• A. The direction of the electron's spin
• B. The energy level of the electron
• C. The orbital shape of the electron
• D. The number of electrons in an orbital

Explanation: The quantum numbers +1/2 and -1/2 represent the direction of the electron's spin.

• A. Max Planck
• B. Neil Bohr
• C. J.J. Thomson
• D. Goldstein
• E. James Chadwick

Explanation: James Chadwick is best known for his discovery of the neutron in 1932, a breakthrough that significantly advanced our understanding of…

• A. Faraday's experiment proved the existence of electrons
• B. Crookes tube experiment shows the presence of electrons and protons in the atoms
• C. Radioactivity confirms the presence of electrons and protons
• D. Chadwick experiment shows the presence of neutrons

Explanation: Option D is correct. Chadwick bombarded a sample of beryllium with alpha particles and observed a new form of radiation that was not…

• A. One node
• B. Two nodes
• C. Three nodes
• D. Zero nodes

Explanation: A node is a region in an orbital where the probability of finding an electron is zero. In a 4s orbital, there are no nodes present.

• A. Has a tight structure
• B. Has high density
• C. Has no free electron in the crystal
• D. Is transparent to light

Explanation: A good conductor has a large presence of free electrons, as they are not bonded strongly to the nucleus, and allow conduction of charges…

• A. An equal number of electrons and neutrons
• B. An equal number of electrons, protons and neutrons
• C. The number of neutrons is double the number of protons
• D. The number of protons is double the number of neutrons.

Explanation: Tritium is the isotope of hydrogen having mass number 3 and proton number 1.

• A. [Xe]4f14, 5d10, 6s1
• B. [Xe]4 f10, 5d10, 6s2
• C. [Xe]4f14, 5d9, 6s2
• D. [Xe]4f14, 5d10, 6s2

Explanation: Atomic number of Au is 79, its electronic configuration is1s22s22p63s23p63d104s24p64d105s25p64f145d106s1(The electronic configuration of…

• A. A
• B. B
• C. C
• D. D

Explanation: Energy gained by the electron when accelerated through a potential of V volts is E=eV This energy is completely converted to kinetic…

• A. Na
• B. Boron
• C. K
• D. Ca

Explanation: A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from the emission or absorption of…

• A. excited state
• B. ground state
• C. cationic form
• D. anionic from

Explanation: The given electronic configuration is ground state for chromium. Hence, (B) is the correct answer.

• A. Cr3+, Fe3+
• B. Fe3+, Mn2+
• C. Fe3+, Co3+
• D. Se3+, Cr3+

Explanation: Fe³+and Mn²+ have same electronic configuration. Hence (B) is the correct answer.

• A. AgNO3 plate
• B. AgC1 plate
• C. ZnO
• D. ZnS

Explanation: Positive rays produce flashes upon ZnS plate.

• A. n = 3, / = 0
• B. n =3, / = 1
• C. n = 2, /.= 1
• D. n = 2, / = 3

Explanation: For 3p subshell quantum number values are n = 3, ℓ = 1.

• A. 3-d is full filled
• B. 3-d is half filled
• C. 1 electron in 4s-orbitals
• D. 8 electrons in s-orbitals

Explanation: So, when we talk about the electronic configuration of copper (Cu) and chromium (Cr), we look at the arrangement of electrons in their…

• A. Aufbau principle
• B. Hund's rule
• C. Paull's exclusion principle
• D. n+I rule

Explanation: Aufbau principle best explains the valency of an element. The Aufbau principle states that electrons fill orbitals in order of increasing…

• A. 6.626 x 10^-34 KJs
• B. 6.262 x 10^-34 Js
• C. 6.626 x 10^-34 Js
• D. 6.262 x 10^-34 KJs

Explanation: The value of planck constant is 6.626 x 10^-34Js.

• A. 4 x 10^-3 m/s
• B. 5 x 10^-4 m / s
• C. 4 x 10^-5 m/s
• D. 4 x 10^-6 m/s

Explanation: We are given:The electron is in a closed cubic box of length L = 10 cm = 0.1 mWe are to find the minimum uncertainty in its velocity…