ECAT Pre Engineering Chemistry Chapter 5 MCQ Test With Answer

The total number of orbitals in a shell with principal quantum number 'n' is

• 2n A
• 2n² B
• n² C
• n + 1 D

• Neutrons are attracted by nucleus A
• Neutrons carry out nuclear reactions B
• Neutrons carry no charge C
• Neutrons are electromagnetic radiations D

The electronic configuration of an atom/ion can be defined by the following

• Aufbau principle A
• Pauli's exclusion principle B
• Hund's Rule C
• All the above 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

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

Pauli's principle is applicable to

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

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

The mass of the neutron is of the order of

• 10^-23 kg A
• 10^-24kg B
• 10^-26kg C
• 10^-27kg 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 number of neutrons in the element ⁹₄Be is

• 4 A
• 5 B
• 9 C
• 13 D

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

• l A
• n B
• m C
• s D

The orbital in Rutherford's model is

• Spiral A
• Circular B
• Both C
• None 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 valence orbital configuration of an element with atomic number 23 is

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

Cathode rays emitted from cathode are

• Canal rays A
• Protons B
• Electrons C
• Positrons 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

Subsidiary quantum number specifies

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

The divisibility of atom was shown by

• Stoney A
• J.J. Thomson B
• Millikan C
• Rutherford D

Splitting of spectral lines when atoms are subjected to strong electron field is called

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

For which of the following sets of quantum numbers and electron will have the highest energy?

• 3,2,1,1/2 A
• 4,2,-1,1/2 B
• 4,1,0,-1/2 C
• 5,0,0,1/2 D

The range of visible spectrum is

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

The e.m value for positive rays maximum for:

• Oxygen. A
• Nitrogen. B
• Helium. C
• Hydrogen. D

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

• 7f A
• 7 s B
• 7 p C
• 7 d D

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

• 3p A
• 3d B
• 3f C
• 3s D

Number of neutrons in heavy hydrogen atom is

• 0 A
• 1 B
• 2 C
• 3 D

E = hv is the

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

Orbital having same energy is called:

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

Which of the following is not isoelectronic?

• Na⁺ A
• Mg²⁺ B
• O^2- C
• Cl^- D