Q82.Which one of the following groupings represents a collection of isoelectronic species? (At. nos,: 55, Br:35) (1) N3−, F−, Na+ (2) Be, Al3+, Cl− (3) Ca2+, Cs+, Br (4) Na+, Ca2+, Mg2+

Q83.In Bohr series of lines of hydrogen spectrum, the third line from the red end corresponds to which one of the following inter-orbit jumps of the electron for Bohr orbits in an atom of hydrogen (1) 5 →2 (2) 4 →1 (3) 2 →5 (4) 3 →2

Q84.The de Broglie wavelength of a tennis ball of mass 60 g moving with a velocity of 10 metres per second is approximately (1) 10−31 metres (2) 10−16 metres (3) 10−25 metres (4) 10−33 metres Planck's constant, h = 6.63 × 10−34Js.

Q79.Which of the following sets of quantum numbers is correct for an electron in 4f orbital? (1) n = 4, l = 3, m = +4, s = + 12 (2) n = 3, I = 2, m = −2, S = + 12 (3) n = 4, I = 3, m = +1, s = + 12 (4) n = 4, I = 4, m −4, s = −12