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 552 of 686
- A. 10 tor
- B. 1 tor
- C. 0.1 tor
- D. 0.01 tor
Explanation: In gas discharge tubes, low pressures are maintained. A common pressure range is around 1 torr.
Correct answer: 1 tor- A. Neutrino
- B. Electron
- C. Both a and b
- D. Meson
Explanation: A free neutron can change into a proton with the emission of an electron.
Correct answer: Electron- A. 1.76 x 10^11 C/kg
- B. 11.76 x 10^11 C/kg
- C. 1.76 x 10^-11 C/kg
Explanation: The value of the charge-to-mass ratio (e/m) of an electron is approximately 1.76×1011 C/kg
Correct answer: 1.76 x 10^11 C/kg- A. Gamma-rays
- B. Aplha -rays
- C. Beta-rays
- D. X-rays
Explanation: Rutherford's famous gold foil experiment, conducted in 1909, involved bombarding alpha particles at a thin gold foil.
Correct answer: Aplha -rays- A. 1s22s22p63s23p64s23d9
- B. 1s22s22p63s25p64s23d7
- C. 1s22s12p23s23p64s23d9
- D. 1s22s22p63s23p64s
Explanation: Copper has an unusual electronic configuration in its ground state. Instead of filling the 4s orbital completely before moving to the 3d…
Correct answer: 1s22s22p63s23p64s23d9- A. Shorter wavelength
- B. Larger wavelength
- C. X-rays not produced
- D. All are possible
Explanation: In general, X-rays produced by an atom with a higher atomic number have shorter wavelengths.
Correct answer: Shorter wavelength- A. Moseley
- B. Davission and Germer
- C. Einstein
- D. Roentgen
Explanation: Through their famous Davisson-Germer experiment. They demonstrated the wave-like properties of electrons through the diffraction of…
Correct answer: Davission and Germer- A. 1s22s22p63s23p64s1
- B. 1s22s23p63s23p24s2
Explanation: The principal quantum number (n) is the quantum number that primarily determines the energy level of an electron in an atom
Correct answer: 1s22s22p63s23p64s1- A. de-Broglie
- B. Planck's
- C. Schrodinger
- D. Heisenberg
Explanation: The three quantum numbers (principal quantum number, azimuthal quantum number, and magnetic quantum number) have been derived from the…
Correct answer: Schrodinger- A. Ice
- B. Carbon (diamond)
- C. Sucrose
- D. Plastic
Explanation: Crystalline substances have a well-defined, repeating three-dimensional arrangement of atoms, ions, or molecules.Plastic: Plastic is a…
Correct answer: Plastic- A. Auf bau principle
- B. Hund's rule
- C. Pauli's Exclusion principle
- D. All
Explanation: Molecular orbitals are filled according to (d) All of the given principles: Aufbau principle, Pauli's Exclusion principle, and Hund's…
Correct answer: All- A. At infinity, the electron is not attracted by nucleus and potential energy is zero
- B. At a point, near the nucleus, its potential energy is less than zero
- C. With the increase of n-value the potential energy increases
- D. All of the above
Explanation: Since options (A), (B), and (C) are all correct statements regarding the potential energy of an electron in an atom under different…
Correct answer: All of the above- A. In the yz plane
- B. In the xy plane
- C. In the y-direction
- D. In the z-direction
Explanation: The pₓ orbital is oriented along the x-axis. The yz plane is a nodal plane for this orbital, meaning it is a plane where the probability…
Correct answer: In the yz plane- A. n=4, l=3, m=3, s=+1/2 or -1
- B. n=3, l=3, m==3, s=+1/2 or -1/2
- C. n=4, l=3, m==3, s=+1/2 or -1/2
- D. =3, l=1, m==0, s=+1/2 or -1/2
Explanation: n=3 represents the third energy level, l=3 indicates an f orbital, m=-3 means the f orbital is oriented in a specific direction, s=+1/2…
Correct answer: n=3, l=3, m==3, s=+1/2 or -1/2- A. n=2,l = 1
- B. n=2, l= 2
- C. n=2, l=0
- D. n=1, l = 0
Explanation: There are two types of quantum numbers: azimuthal quantum number(l) and principal quantum number(n).
Correct answer: n=2,l = 1- A. Faraday's experiments proved the existence of electrons
- B. Crookes tube experiment demonstrated the presence of electrons in the atoms
- C. Radioactivity directly confirms the presence of electrons and protons
- D. Chadwick's experiment confirmed the presence of neutrons
Explanation: Option D is correct. James Chadwick's experiment involving the bombardment of beryllium with alpha particles led to the discovery of…
Correct answer: Chadwick's experiment confirmed the presence of neutrons- A. 0.2m
- B. 0.2 nm
- C. 2 x 10^-19nm
- D. 0.2 pm
Explanation: The diameter of an atom is 0.2nm. PTB-Pg 2
Correct answer: 0.2 nm- A. [Ar] 4s2
- B. [Ar] 4s1
- C. [Kr] 4s1
- D. [He] 4s1
Explanation: The Potassium electron configuration will be 1s22s22p63s23p64s1. The electronic configuration of Argon is 1s22s22p63s23p6
Correct answer: [Ar] 4s1- A. 4s<3s<2s3s>2s>ls
- B. 4s>3s> 2s> 1s
- C. Constant
- D. None of these
Explanation: The s subshell has 1 orbital that can hold up to 2 electrons, the p subshell has 3 orbitals that can hold up to 6 electrons, the d…
Correct answer: 4s>3s> 2s> 1s- A. 2.8 × 10−18 J/atom
- B. 0.545 × 10−18 J/atom
- C. −2.18 × 10−18 J/atom
- D. −1312.36 J/atom
Explanation: By using the formula for the energy of an electron in the nth orbitEn=-{me-4Z2/8 ε2 h2 n2}For hydrogen Z=1 and by putting values of…
Correct answer: 0.545 × 10−18 J/atom