All Free Chemistry MCQs with Answers
Every Chemistry question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
13,720 questions · page 684 of 686
- A. Microwave
- B. Infrared
- C. Visible
- D. X-rays
Explanation: The difference in energy between two vibrational states is equal to the energy associated with the wavelength of radiation that was…
Correct answer: Infrared- A. Molecule may gain an electron to form a molecular anion.
- B. Molecule may lose an electron to form a molecular cation.
- C. Molecular cations are less abundant than molecular anions.
- D. These molecular ions can be formed by passing a high-energy electron beam through a gas.
Explanation: Abundance of cationic molecular ions is due to the ability to stabilize unpaired electrons which makes the formation of cationic molecular…
Correct answer: Molecular cations are less abundant than molecular anions.- A. The most direct and accurate method for determining atomic masses uses mass spectrometry.
- B. An indirect but precise method for determining molecular masses is through mass spectrometry.
- C. Collision between electrons and atoms produces negative ions by the absorption of electrons by atoms or molecules.
- D. The first significant application of mass spectrometry was demonstrating the detection of isotopes of Argon.
Explanation: Electron Collision. Often, electron collisions with gas molecules result in electron attachment to the molecule, which forms a negative ion.
Correct answer: Collision between electrons and atoms produces negative ions by the absorption of electrons by atoms or molecules.13664. Molar extinction coefficient (ε) a constant in Beer- Lambert law is the characteristics of the:
- A. Solute
- B. Solvent
- C. Concentration
- D. All of the above
Explanation: Under defined conditions of solvent, pH, and temperature the molar absorption coefficient for a particular compound is a constant at the…
Correct answer: All of the above- A. Accurate but more time consuming
- B. Accurate, rapid but chemicals are used in large amounts
- C. Accurate, rapid but sophisticated and complicated
- D. Accurate, simple and less time consuming
Explanation: The modern methods used by scientists to identify and differentiate between cell structures are efficient, accurate, simple, and less…
Correct answer: Accurate, simple and less time consuming- A. Microwave
- B. Radio wave
- C. Infrared region
- D. X-rays
Explanation: NMR spectroscopy works by applying a radio frequency to the sample, specific to the nuclei of interest.
Correct answer: Radio wave- A. σ - σ
- B. d - d
- C. π - π
- D. π - σ
Explanation: d-d transitions are electronic transitions that occur between the molecular orbitals that are mostly metallic in character; specifically…
Correct answer: d - d- A. No absorption
- B. 50% absorption
- C. 75% absorption
- D. 100% absorption
Explanation: When IR radiation is passed through a sample, some of it is absorbed and some of it paasses through (transmitted).
Correct answer: No absorption- A. δ = 10 - t
- B. δ = 10 + t
- C. t = δ - 10
- D. t = 10 - δ
Explanation: In NMR spectroscopy, δ (delta) represents the chemical shift, while t is another scale used to express the same concept.
Correct answer: δ = 10 - t- A. Mg (NO3)2
- B. Mg (ClO4)2
- C. Mg (OH)2
- D. Mg (ClO2)2
Explanation: The correct answer is Mg (ClO4)2, or magnesium perchlorate, which is widely used in combustion analysis as a drying agent due to its…
Correct answer: Mg (ClO4)2- A. Different energies
- B. Equal energies
- C. Zero energies
- D. High energies
Explanation: In the absence of an applied magnetic field, the spin states of a nucleus of an atom have equal energies.
Correct answer: Equal energies- A. 500 - 1300 cm-1
- B. 600 - 1500 cm-1
- C. 1500 - 4000 cm-1
- D. 2500 - 3500 cm-1
Explanation: The functional group region in an infrared spectrum ranges from 1500 to 4000 cm-1.
Correct answer: 1500 - 4000 cm-1- A. Wavelength
- B. Wavenumber
- C. Frequency
- D. All of the above
Explanation: The correct answer is All of the above. Infrared spectra can be expressed in terms of wavelength, wavenumber, or frequency, each offering…
Correct answer: All of the above- A. Red Colour
- B. Green Colour
- C. Ultra Voilet
- D. None of the above
Explanation: The answer is D as all the mentioned radiations can excite molecules.All electromagnetic radiation, including red and green colours of…
Correct answer: None of the above- A. 2
- B. 6
- C. 4
- D. 8
Explanation: In isopropyl chloride, there are 6 different types of "NMR" protons. This means that there are 6 unique environments for the protons in…
Correct answer: 6- A. Mass Spectroscopy
- B. NMR Spectroscopy
- C. IR Spectroscopy
- D. U.V Visible Spectroscopy
Explanation: Among the options provided, NMR (Nuclear Magnetic Resonance) Spectroscopy gives more detailed information about the structure of an…
Correct answer: NMR Spectroscopy- A. Negative (-Ve)
- B. Positive (+Ve)
- C. Zero
- D. None
Explanation: In the hydrogen atom, the force we are primarily referring to is the attractive force acting between the nucleus and the electron and this…
Correct answer: Negative (-Ve)13678. The ionization energy of a hydrogen atom is 13.6 ev. The ionization potential required will be:
- A. 4.9 volt
- B. 8.5 * 10-10 volt
- C. 3.4 volt
- D. 13.6 volt
Explanation: The ionization energy of a hydrogen atom is the energy required to remove an electron from the atom.
Correct answer: 13.6 volt- A. Zero
- B. Negative
- C. Positive
- D. None of the above
Explanation: The energy of a hydrogen atom in its ground state is negative, approximately -13.6 eV.
Correct answer: Negative- A. -13.6eV
- B. -3.4eV
- C. -0.85eV
- D. -1.5eV
Explanation: The energy of an electron in the excited state with n=4 in a hydrogen atom can be calculated by using the formula for the energy levels of…
Correct answer: -0.85eV