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

The order of frequency of the following radiations unltraviolet, visible, infrared and microwave is

• Microwave > infrared > visible > ultraviolet A
• Visible > ultraviolet > microwave > infrared B
• Ultraviolet > visible > infrared > microwave C
• Infrared > microwave > ultraviolet > visible D

• s A
• p B
• d C
• f D

An electron with n = 3 , l = 2 will be in the sub-shell

• 3p A
• 3d B
• 3f C
• 3s D

When the electron jumps form second third, fourth orbit to the fist orbit, the transitions are known as

• Balmer series A
• Lyman series B
• Pfund series C
• Brackett series D

When electron jumps from n₂= 2,3,4,5,.... orbit to n₁= 1 orbit in the hydrogen atom, the radiations emitted give the spectral lines

• Lyman series A
• Blamer series B
• Paschen series C
• Brackett series D

Sodium chloride imparts a yellow colour to the Bunsen flame. This can be interpreted due to the

• low ionization energy of sodium A
• sublimation of metallic sodium to give yellow vapour B
• emission of excess energy absorbed as a radiation in the visible region as a radiation in the visible region C
• photosenitivity 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

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

Pauli's principle is applicable to

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

In Millikan method for determination of charge on electron the air in the chamber is ionized by

• Protons A
• Electric field B
• X-rays C
• a - particles D

Proton was discovered by:

• Chadwick A
• J.J. Rhomson B
• Millikan. C
• Goldstein. D

Splitting of spectral lines of the hydrogen atom under the influence or magnetic field is called

• Stark effect A
• Zeeman effect B
• Compton effect C
• Photoelectric effect D

Orbitals having same energy are called

• Hybrid orbitals A
• Valence orbitals B
• Degenerate orbitals C
• D-orbitals D

The radius of second Bohr's orbit is

• 0.053 nm A
• 0.053/4 nm B
• 0.053 x 4 nm C
• 0.053 x 20 nm D

The valence orbital configuration of an element with atomic number 23 is

• 3d⁵ A
• 3d³, 4s² B
• 3d³, 4s¹, 4p¹ C
• 3d²,4s²,4p¹ D

The nature of positive ray depend on:

• The nature of electrode. A
• The nature of discharge tube. B
• The nature of residual gas. C
• All of above. D

The radius of first orbit of hydrogen atom

• 0.329 A° A
• 0.429 A° B
• 0.529 A° C
• 0.229 A° D

Number of neutrons in heavy hydrogen atom is

• 0 A
• 1 B
• 2 C
• 3 D

The charge of an electron is determined by

• J.J. Thomson A
• Crooks B
• Perrin C
• R.A.Millikan 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

Effective magnetic moment of Sc³⁺ion is

• 1.73 A
• 0 B
• 5.92 C
• 2.83 D

The principle quantum number describes

• The distance form the nucleus A
• The shape of the orbital B
• The orientation of the orbital C
• The spin of the electron D

Which one of the following statements is true about discovery of neutrons?

• These particles were formed by the bombardment of Alpha-particles on Beryllium. A
• These particles are formed by the spiting of alpha-particles. B
• These particles were discovered by natural radioactivity. C
• None of above. D

Subsidiary quantum number specifies

• size of orbital A
• shape of orbital B
• orientations of orbitals C
• Nuclear stability D

When an electric current is passed through discharge tube at low pressure, cathode rays are emitted from cathode these rays consist of:

• Alpha rays. A
• Negative particles. B
• Electromagnetic rays. C
• Positive particles. D

The nature of the positive rays depend on

• The nature of the electrode A
• The nature of the discharge tube B
• The nature of the residual gas C
• All of the above D

The size of electronic shell is described by

• Azimuthal Q. no A
• Magnetic Q.No B
• Spin Q. No C
• Principle Q. No D

The value of charge on electron is

• 1.602 x 10^-19coulombs A
• 1.602 x 10^-18coulombs B
• 1.602 x 10^-17coulombs C
• 1.602 x 10^-16 coulombs D

Which of the following is not a sub-atomic particle

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