ECAT Pre Engineering Chemistry Chapter 5 MCQ Test With Answer

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

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

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

Alpha rays consist of:

• Neutrons. A
• Helium nucleus. B
• Protons. C
• Hydrogen nucleus. 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

Charge on electron was discovered by:

• Millikan. A
• Crook. B
• Neil Bohr. C
• Rutherford. D

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

• Paschen A
• Pfund B
• Balmer C
• Brackett D

Charge of an electron is:

• 1.6 x 10^-19 C

  A

• 9.1 x 10^-34 C

  B

• 1.7588 x 10¹¹ C

  C

• 6.62 x 10^-34 C

  D

Positive particle in discharged tube is produced by ionization of gas molecules, which is caused by

• Gas molecules collide with anode A
• Gas molecules are at high temperature B
• Gas molecules produce X-rays C
• Cathode rays remove electrons from gas molecules D

The arrangement of subshells in the ascending order of their energy on complete filing of 4f subshell the entering electrons goes to

• 5s A
• 5p B
• 5d C
• 5f D

Their e/m, ratio resembles with that of electrons

• Alpha rays A
• Beta rays B
• Gamma rays C
• X-rays D

No cathode rays are produced in the discharged tube when gas is under ordinary pressure even if voltage of 5000 to 10000 is applies. This reason is

• Voltage is low A
• Discharge tube is not coloured B
• Gas does not conduct current under ordinary pressure C
• Temperature low D

With increasing principle quantum number, the energy difference between adjacent energy levels in H atom

• Decreases A
• Increases B
• Remains constant C
• Decreases for low value of Z and increase for higher value of Z D

Neutron was discovered by:

• Chadwick. A
• Bohr. B
• Rutherford. C
• Plank. D

The range of visible spectrum is

• 300 - 600 nm A
• 600 - 900 nm B
• 400 - 750 nm C
• 100 - 300 nm D

When 6d orbital is complete, the entering electron goes into:

• 7f. A
• 7s. B
• 7p. C
• 7d. D

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

• n A
• n² B
• 2n C
• 2n² D

In the ground state of an atom the electron is present

• In the nucleus A
• In the second shell B
• Nearest to the nucleus C
• Farthest from the nucleus D

In which of the following pairs, the numbers of electrons in the outermost shell are different?

• As,Sb A
• Ge,Sn B
• In,pt C
• Se,Te D

• s A
• p B
• d C
• f D

The charge of an electron is determined by

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

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 third line of the Balmer series, in the emission spectrum of the hydrogen atom,is due to the transition from the

• Fourth Bohr orbit to the first Bohr orbit A
• Fifth Bohr orbit to the second Bohr orbit B
• Sixth Bohr orbit to the third Bohr orbit C
• Seventh Bohr orbit to the third Bohr orbit D

Which quantum number is sufficient to describe the electron is hydrogen atom?

• l A
• n B
• m C
• s D

Which of the following is not isoelectronic?

• Na⁺ A
• Mg²⁺ B
• O^2- C
• Cl^- 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

The total values of magnetic quantum number of subshell are five, the subshell is

• S-subshell A
• P-subshell B
• D-subshell C
• F-subshell D

Which of the following is not charged particle

• Proton A
• Electron B
• Neutron C
• Hydrogen nucleus D

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

• 3p A
• 3d B
• 3f C
• 3s D

Subsidiary quantum number specifies

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