2

Q1. Zeeman effect is the splitting of spectral line in presence of:

• electric field
• electricity
• magnetic effect
• molecule

Solution

Zeeman effect is the splitting of spectral line in presence of magnetic field.

Q2. Which quantum numbers must be the same for the orbitals so that they are designated to be degenerate in a one-electron system (like hydrogen)?

• n and m
• n and l only
• l and m
• m only

Solution

The degenerate orbitals are orbitals of a particular sub shell which will have same energy in an atom.

Q3. The de Broglie wavelength of a tennis ball of mass 50 g moving with a velocity of 10 m/s is approximately

• 0.132 x 10^-30 m
• 0.132 x 10^-20 m
• 0.132 x 10^-22 m
• 0.132 x 10^-32 m

Solution

Using the formula,

Q4. By use of a suitable filter, the green mercury emission line can be isolated. This line has a wavelength of 546.1 nm. What is the frequency? [1 Hz = 1 s^-1]

• 0.0054 x 10¹⁷ Hz
• 1.820 x 10⁴ Hz
• 5.461 x 10^-7 Hz
• 1.820 x 10^-13 Hz

Solution

  Using the formula.  

Q5. Simultaneous determination of exact position and momentum of an electron is:

• Possible
• Not possible
• Sometimes possible and sometimes impossible
• Momentum cannot be determined

Solution

Simultaneous determination of exact position and momentum of an electron is not possible. This is according to Heisenberg's uncertainty principle.

Q6. The de Broglie wavelength of an electron is 8.7 x 10^-11 m. The mass of an electron is 9.1 x 10^-31 kg. The velocity of this electron is:

• 8.4 × 10³ m/s
• 1.2 × 10^-7 m/s
• 6.9 × 10^-5 m/s
• 8.4 x 10⁶ m/s

Solution

Using the formula,  

Q7. A subshell with n = 6, ℓ = 2 can accommodate a maximum of

• 12 electrons
• 36 electrons
• 10 electrons
• 72 electrons

Solution

ℓ = 2 correspond to d orbitals thus there are 5 orbitals.Each orbtial can accommodate 2 electrons. So in all there are 5 X 2 = 10 electrons.  

Q8. Which set of quantum numbers is correct with n = 3?

• l = 2, m_l = +3, m_s = +1/2
• l = 3, m_l = +2, m_s = 1
• l = 2, m_l = +2, m_s = +1/2
• l = 1, m_l = +3, m_s = +1/2

Solution

For given n,  the possible l values are 0, 1, and 2. For l =0, possible m_l values is 0.  For l =1, possible m_l values are: +1,0, -1. For l =2, possible m_l values are: +2,+1,0, -1,-2 There are two possible m_s values for each m_l value: +1/2 or -1/2

Q9. Which pair of species has the same number of electrons?

• Fe, Mn⁺
• Te, Se
• Ar, K⁺
• Mn, Tc

Solution

Argon has atomic number 18. i.e number of electrons = 18 and in the same way K⁺ = 19 - 1 = 18.

Q10. Which of the following orders of increasing energy of orbitals is incorrect?

• 3s < 4s < 5s
• 5s < 4d < 5p
• 6s < 4f < 5d
• 6s < 4p < 6p

Solution

The sub shell which has lower value of (n+l ) is always given priority for filling of electrons.

Q11. Which of the following statements is correct about the wave number?

• It is the distance travelled by a wave in one second.
• It is defined as the number of wavelengths per unit length.
• It is defined as the number of waves which pass through a particular point in one second.
• It is defined as the distance between two neighbouring crests or troughs of wave.

Solution

Wave number is defined as the number of wavelengths per unit length.  

Q12. The charge on electron was determined by

• Bohr
• Milliken
• Schrodinger
• Crooks

Solution

The charge on electron was determined by Milliken by his Oil Drop Experiment.

Q13. Which of the subshells below do not exist due to the constraints upon the azimuthal quantum number?

• 2d
• 2s
• 2p
• 4d

Solution

The principal quantum no. n = 2 can not have l = 2.

Q14. The ejected electrons from the surface of metal in photoelectric effect are called

• Electron
• Photoelectrons
• Proton
• Neutron

Solution

The ejected electrons from the surface of metal in photoelectric effect are called photoelectrons.

Q15. The wavelength of light that has a frequency of 1.20 × 10¹³s^-1 is __________ m.

• 25.0
• 2.50 × 10^-5
• 0.0400
• 12.0

Solution

The speed of all form of electromagnetic wave is related by the equation c = λ.v, whereby, λ = 3.0 x 10⁸ / 1.2 x 10¹³ = 2.5 x 10 ^-5 m.

Q16. The shape of a 3p orbital resembles:

• Dumbbell
• Double spherical
• A circle
• A sphere

Solution

3p orbitals have two separate lobes. The electron density is exactly zero at the nucleus. The orbital is oriented along the x, y and z axis, there are three 3p orbitals.

Q17. Which one of the following represents an impossible arrangement for the values of n, l, m_l and m_s?

• 3, 2, -2, 1/2
• 4, 0, 0, -1/2
• 3, 2, -3, 1/2
• 5, 3, 0, -1/2

Solution

The possible value of m varies from -l to +l .For example: the possible values of m for l = 2 are -2, -1, 0, +1, +2.

Q18. In which pair is the two species Isoelectronic?

• Fe²⁺, Fe³⁺
• O, N^-
• As, P
• O, F

Solution

Oxygen has atomic number 8 i.e. number of electrons = 8. Similarly, N^- = 7 + 1 = 8.

Q19. What is the energy of a photon that has a wavelength of 12.3 nm?

• 1.51 × 10^-17 J
• 4.42 × 10^-23 J
• 1.99 × 10^-25 J
• 1.6 x 10^-17J

Solution

Q20. Which quantum number determines the radius of an atom?

• n
• m
• l
• n and l

Solution

Principal quantum number(n) signifies the distance from the nucleus and the size of an atom.

Q21. De Broglie proposed that -

• Matter consists of microscopic particles
• Matter should exhibit particle nature Only
• Matter should exhibit both particle and wave nature
• Matter consists of microscopic paricles

Solution

De - Broglie proposed that matter like radiation should exhibit both particle and wave nature.

Q22. Many home bathrooms have infrared light fixtures to help warm the room, and this light is not cancer causing. Which of the following quality make it so useful?

• The amplitudes of these waves are short
• The wavelength of IR rays is longer
• The energy of IR light is greater
• The temperature of the IR light

Solution

Photons of IR rays have low energy because of longer wavelength.

Q23. Which of the following subatomic particles is responsible for the spectrum of radiation emitted by an element or a compound?

• Proton
• Electron
• Neutron
• Photon

Solution

Electron transition from higher to lower energy levels cause photons to emit radiation.

Q24. Which one of the following statements does apply to atoms which are isotopes of the same element?

• The sum of the number of protons and neutrons is the same.
• The sum of the number of electrons and neutrons is the same.
• The number of electrons outside the nucleus is the same.
• The mass numbers are the same.

Solution

Isotopes are atoms of the same element having same number of protons/electrons but different number of neutrons.

Q25. Total number of orbitals in a shell is given by

• n³
• 3n²
• n²
• n⁴

Solution

Total number of orbitals in a shell is given by n². 

Q26. Which of the following is true about an electron?

• It is negatively charged and is lighter than a proton.
• It is negatively charged and has same mass as a proton.
• It is positively charged and has no mass
• None of the above

Solution

An electron is negatively charged and has much smaller mass than that of a proton.  

Q27.   What information does Ψ indicate about wave?  

• Velocity
• Region of maximum electron density
• Amplitude
• Frequency

Solution

Ψ gives us the amplitude of wave. It has no physical significance.

Q28. What experimental result did Albert Einstein cite as evidence that light has particle-like properties?

• The orbits of electrons within the hydrogen atom could have only certain radii.
• The fact that electrons posses both particle and wave-like properties.
• The ejection of electrons from a metal surface by light depends only on the frequency of the light used.
• The pattern of light and dark bands produced when light was passed through a pair of narrow slits.

Solution

Albert Einstein was able to explain the phenomenon of photoelectric effect on this assumption.

Q29.   Calculate the value of azimuthal quantum number for the subshell notation 4d?

• 4
• 3
• 2
• 1

Solution

For d, the value of azimuthal quantum number is 2.

Q30. The fundamental subatomic particle neutron was discovered by

• Rutherford
• Max Planck
• Heisenberg
• Chadwick

Solution

The neutron was discovered by James Chadwick by bombarding a thin sheet of beryllium by α-particles.

Q31. An orbital is identified by how many quantum numbers?

• 1
• 2
• 3
• 4

Solution

An orbital is identified by 3 quantum numbers i.e Principal quantum number, azimuthal quantum number and magnetic quantum number.

Q32. Anode rays were discovered by

• E. Rutherford
• J.J. Thomson
• E. Goldstein
• J. Chadwick

Solution

Goldstein (1900) discovered protons in Anode Ray experiments. Atoms contain positively charged particles called protons. Since atoms contain negatively charged particles, they must contain positively charged particles for them to be electrically neutral.

Q33. It takes 495.8 kJ/mol of energy to ionize sodium. What frequency (s^-1) and wavelength (nm) of light would be required to ionize sodium?

• frequency (s^-1) wavelength (nm) 7.48 x 10³⁸ 241
• frequency (s^-1) wavelength (nm) 1.24 x 10¹⁵ 2.41 x 10⁴
• frequency (s^-1) wavelength (nm) 1.24 x 10¹⁵ 241
• frequency (s^-1) wavelength (nm) 7.48 x 10³⁸ 3.95 x 10^-22

Solution

We use v = E /N_A X h = 1.24 x 10¹⁵ s^-1 and λ = c/v = 241 nm

Q34. If the value of azimuthal quantum number is 3, the possible values of magnetic quantum numbers would be:

• 0, 1, 2, 3
• 0, -1, -2, -3
• 3, -2, -1, 0, +1, +2, +3
•  3, -2, -1, +1, +2, +3

Solution

The total possible values of m for l range from -l through 0 to +l.

Q35. Which of the following spectral series of line spectrum of hydrogen atom belongs to the ultra violet region?

• Lyman
• Balmer
• Paschen
• Brackett

Solution

Lyman series belong to ultraviolet region.

Q36. Thomson's plum pudding model explained:

• Existence of electrons
• Existence of protons
• Electrons move in fixed circular orbits
• Electrical neutrality of an atom

Solution

The Thomson's pudding model explained that atoms were spheres of positive charge with electrons embedded in it.

Q37. The radius of an atom is approximately

• 10^-12 cm
• 10^-10  m
• 1 nm
• 1 cm

Solution

The radius of an atom is approximately 10^-10 m.

Q38. What is the frequency of light in s^-1 that has a wavelength of 3.12 x 10^-3 cm?

• 3.69
• 2.44 × 10¹⁶
• 9.62 × 10¹²
• 1.04 ×10¹³

Solution

The wavelength (λ) and frequency (ν) of electromagnetic wave is related by the equation c = λ.ν, Where c is the speed of light = 3.00 x 108 m/s, λ is the wavelength in m and ν is the frequency is s^-1 or Hz. Substituting the values in the formula, we get, c = λ.ν ν = c/λ ν = 3.0 x 10⁸ / 3.12 x 10^-5    = 0.96 x 10¹³ m  

Q39. The shape of the p_x orbital is:

• Spherical
• Octahedral
• Dumb-bell
• Double Dumb-bell

Solution

All p orbitals are dumb-bell in shape.

Q40. How much energy is needed to ionize a hydrogen atom if electron is present in n=1 orbit?

• 13.6 eV
• 10.2 eV
• 3.4eV
• 1 eV