General
✓✗The outer electronic configuration of Gd (atomic number 64) is
- 4f4 5d5 6s1
- 4f7 5d1 6s2
- 4f3 5d5 6s2
- 4f5 5d4 6s1
General
✓✗146C and 168O are
- isotones
- isoelectronic
- isotopes
- isobars
General
✓✗Which transition in the hydrogen atom gives a line in the infrared region?
- n = 3 → n = 2
- n = 2 → n = 1
- n = 5 → n = 3
- n = 4 → n = 1
General
✓✗Hund's rule states that pairing of electrons in orbitals of the same subshell
- takes place before single occupation
- occurs only in s orbitals
- never occurs
- does not take place until each orbital is singly occupied
General
✓✗The ratio of the wavelengths of the light absorbed by a hydrogen atom when it undergoes the n = 2 → n = 3 and n = 4 → n = 6 transitions, respectively, is
- \( \dfrac{1}{4} \)
- \( \dfrac{1}{36} \)
- \( \dfrac{1}{16} \)
- \( \dfrac{1}{9} \)
General
✓✗Radiation of frequency 6 × 1014 Hz falls in the
- microwave region
- visible region
- X-ray region
- radio region
General
✓✗The de Broglie wavelength of an electron moving with a velocity of 1 × 106 m s−1 is about (h = 6.626 × 10−34 J s, me = 9.1 × 10−31 kg)
- 0.073 nm
- 73 nm
- 7.3 nm
- 0.73 nm
General
✓✗The radius of the first Bohr orbit of hydrogen is
- 529 pm
- 52.9 pm
- 5.29 pm
- 0.529 pm
General
✓✗The circumference of the third Bohr orbit of hydrogen equals
- one de Broglie wavelength
- three de Broglie wavelengths of the electron
- nine de Broglie wavelengths
- one-third of a de Broglie wavelength
General
✓✗The ratio of the number of neutrons to the number of protons is the highest in
- 23892U
- 126C
- 5626Fe
- 168O
General
✓✗The radius of the second Bohr orbit of He+ is
- 52.9 pm
- 211.6 pm
- 105.8 pm
- 26.45 pm
General
✓✗In Bohr's model, the time period of revolution of the electron is proportional to
- n/Z
- n2/Z
- n3/Z2
- Z2/n3
General
✓✗According to Bohr, the angular momentum of an electron in a stationary orbit is
- continuous
- an integral multiple of h/2π
- zero
- an integral multiple of h
General
✓✗Who modified Bohr's theory by introducing elliptical orbits for the electron path?
- Thomson
- Hund
- Rutherford
- Sommerfeld
General
✓✗The positions of both an electron and a helium atom are known within 1.0 nm. Further, the momentum of the electron is known within 5.0 × 10−26 kg m s−1. The minimum uncertainty in the measurement of the momentum of the helium atom is
- 50 kg m s−1
- 8.0 × 10−26 kg m s−1
- 80 kg m s−1
- 5.0 × 10−26 kg m s−1