ECAT Pre Engineering Chemistry Chapter 5 MCQ Test With Answer

If the radius of first Bohr orbit be a_o, then the radius of third Bohr orbit would be

• 3 x a_o A
• 6 x a_o B
• 9 x a_o C
• 1/2 x a_o D

Pauli's principle is applicable to

• Degenerate orbits A
• Two electrons in the same orbital B
• One electron C
• None D

The order of distance between the various Bohr orbits is

• r₂- r₁> r₃- r₂> r₄- r₃> ...... A
• r₁> r₂> r₂- r₃> r₄-r₃> ..... B
• r₂-r₁= r₃- r₂= r₄- r₃> ..... C
• r₂- r₁> r₃- r₂< r₄- r₃< .... D

For a 3P subshell the set of principle and azimuthal quantum number is

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

Maximum potential energy that an electron can have within the atom is:

• Equal to zero. A
• Less than zero. B
• Greater than zero. C
• Infinite D

Charge to mass ratio of electron was discovered by:

• Millika. A
• Rutherford. B
• J.J. Thomson. C
• Chadwick. D

Which of the following was discovered first:

• Charge to mass ratio of electrons. A
• Mass of electrons. B
• Charge of electrons. C
• All of above at same time. D

Mass of simple electron is:

• 9.1 x 10^-31 kg

  A

• 9.1 x 10^-30 kg

  B

• 1.66 x 10^-31 kg

  C

• 9.1 x 10^-31 kg

  D

The value of R (Rydberg's constant) is _______ m-1

• 1.0974 x 107 A
• 1.0842 x 107 B
• 1.082 x 10-7 C
• Both a and b D

E = hv is the

• Spectral equation A
• Plank's equation B
• de Broglie's equation C
• None of these D

In Millikan method the oil droplet falls under the force of gravity but it moves upward due to

• Electric field A
• Magnetic field B
• Incident light C
• X-rays D

The total number of orbitals possible for the quantum number n is

• n A
• n² B
• 2n C
• 2n² D

The quantum number which describes the shape of the orbital is

• Principle quantum number A
• Spin quantum number B
• Azimathal quantum number C
• Magnetic quantum number D

The experimental evidences for the existence of atomic nucleus comes from:

• Line spectrum of hydrogen. A
• Magnetic bonding of cathode rays. B
• Millikan oil drop experiment. C
• Scattering of alpha particles by thin metal foil. D

When the 6d orbital is completed the entering electron goes into

• 7f A
• 7 s B
• 7 p C
• 7 d D

Negatively charged particle nature of cathode rays was first demonstrated in 1895 by:

• Millikan. A
• J. Perrin. B
• Hittrof C
• J.J. Thomson. D

Energy of electron in first orbit of H atom is

• -45.32 KJ/mole A
• -82.08 KJ/mole B
• -52.53 KJ/mole C
• -1313.31 KJ/mole D

n + l value for 4f will

• 2 A
• 5 B
• 7 C
• 9 D

Rutherford's planetary like picture of the atomic modal was defective because

• It did not describe the quantity of positive charge A
• It did not explain the repulsion of protons within the nucleus B
• No empty space between nucleus and the electrons C
• Moving electron should radiate energy D

The radiations with wavelength shorter than violet light are called

• Ultraviolet A
• Infrared B
• Microwave C
• Radio frequency D

The spectrum of helium is expected to be similar to that of

• H A
• Li⁺ B
• Na C
• He⁺ D

Orbital having same energy is called:

• Hybrid orbital. A
• Valence orbital. B
• Degenerate orbital. C
• D-orbital. D

An orbital can accommodate maximum two electrons with opposite spins according to

• Heisenberg's principle A
• Aufbau principle B
• Hund's srule C
• Pauli exclusion principle D

In the ground state, an element has 13 electrons in its M shell. The element is

• Copper A
• Chromium B
• Nickel C
• Iron D

Which of the following is not a sub-atomic particle

• Electron A
• Proton B
• Neutron C
• Deuteron D

Smallest charge of electricity that has been measured so far is

• Charge on a-rays A
• Charge on electron (1.602 x 10^-19C) B
• Charge on x-rays C
• Charge on gamma rays D

The limiting line of Blamer series in hydrogen spectrum lies in

• Visible regions A
• Ultraviolet region B
• Infrared region C
• x-rays region D

Charge to mass ratio (e/m) of the electron is determined by

• R. A. Millikan A
• J. J. Thompson B
• G. J, Stoney C
• None of these D

• Plank's equations A
• de Broglie's equations B
• Heisenburg's equation C
• None D

Neutrons was discovered by

• Mosely A
• Milliken B
• Chadwick C
• Ruherford D