In an atom valence electron are present in:
  • Anyone of its orbit
  • Next to outermost orbit
  • Outermost orbit
  • First orbit
Which would be the electrical charge on a sulphur atom-containing 18 electrons?
  • \(1^-\)
  • \(2^+\)
  • 0
  • \(2^-\)
Which of the following isotopes is used as the standard for atomic mass?
  • 12 C
  • 13 C
  • 16 O
  • 1 H
In an atom, the constituent electrons:
  • Are uniformly distributed
  • Move around the nucleus in fixed energy levels.
  • Move around the nucleus in a random way.
  • Do not move
Which of the following statements is not correct for Bohr’s model of an atom?
  • The nucleus of an atom is situated at ts center
  • Electrons jump from one orbit to another
  • The electrons move in circular orbits
  • An electron neither loses nor gains energy it jumps from one orbit to another.
A natural phenomenon that supports the experimental conclusion that atoms are divisible is:
  • Allotropy
  • Radioactivity
  • Cracking
  • None of these
The cathode ray experiment was done for the first time by:
  • Goldstein
  • J.J. Thomson
  • Rutherford
  • John Dalton
What is the number of valence electrons of Al?
  • 4
  • 2
  • 3
  • 1
The number of electrons in an element with atomic number X and atomic mass Y will be:
  • (X + Y)
  • X
  • (X - Y)
  • (Y - X)
Which of the following statements is incorrect for cathode rays?
  • They cost shadow of solid objects placed in their path
  • They move in a straight line
  • They get deflected towards positive charge.
  • Their nature depends upon the nature of the gas present in the discharge tube.
When a \(\beta\)-particle is emitted, the atomic number of the daughter elements is one unit more as compared to that of the parent element. This increase in atomic number is due to:
  • Addition of a proton to the nucleus
  • Removal of an electron from the nucleus
  • The decay of neutron present in the nucleus
  • Any one of the above
Which of the following describes an isotope with a mass number of 99 that contains 56 neutrons in its nucleus?
  • 99Ba56
  • 56Tc43
  • 99Tc43
  • 43Ba56
By whom was neutron discovered?
  • Rutherford
  • Chadwick
  • Dalton
  • Bohr
Members of which of the following have similar chemical properties?
  • Isobars
  • Allotropes
  • Isotope
  • Both isotopes and allotropes
17Cl35 and 17Cl37 are examples of:
  • Isobars
  • Isotopes
  • Isoelectronic atoms
  • None of the above
Which one of the following statement is not true?
  • The total number of neutrons and protons is always equal in a neutral atom
  • Most of the space in an atom is empty
  • The total number of electrons and protons in an atom is always equal
  • The total number f electrons in any energy level can be calculated by the formula 2n2
5525Mn++ has:
  • 25 protons and 30 neutrons
  • 25 neutrons and 25 protons
  • 25 electrons and 40 protons
  • None of the above
Which of the following electronic configurations is wrong?
  • Be (3) = 2, 1
  • S (16) = 2, 6, 8
  • P (15) = 2, 8, 5
  • S (16) = 2, 6, 8
The fluorescence on the walls of discharge tube is due to:
  • Cathode rays
  • Anode rays
  • Canal rays
  • None of the above
The correct representation of 3 molecules of chlorine is:
  • 2Cl3
  • 3 Cl2
  • 6 CI
  • Cl6
13Al27 is a stable isotope. 13Al29 is expected to disintegrate by:
  • α emission
  • β emission
  • Positron emission
  • Proton emission
The four quantum numbers that could identify the third 3p electron in sulphur are:
  • N = 3, 1 = 1, m = -1, s = +1/2
  • N = 2, 1 = 2, m = -1, s = -1/2
  • N = 3, 1 = 0, m = +1, s = +1/2
  • N = 3, 1 = 2, m = +1, s = -1/2
n/p ratio of an element with atomic number greater tha 83 falls in the zone of instability. The element will undergo:
  • β+ -decay
  • No decay
  • β -decay
  • α - decay
Which of the following orbital is more close to the nucleus?
  • 5f
  • 6d
  • 7p
  • 7s
Aluminum has a valence of 3 and sulphate has a valence ofTherefore, the correct formula for aluminum sulphate is:
  • AlSO4
  • Al3 (SO4)2
  • Al2 (SO4)3
  • Al2S2O4
Which of the following nuclides is least likely to be stable?
  • 25Mn55
  • 13AL30
  • 50Sn119
  • 20C40
The shortest wavelengths of radiation emitted when can electron from infinity falls into the ionized H-atom(RH = 1.097 x 107 m-1)
  • 91 nm
  • 192 nm
  • 406 nm
  • 1.9 x 10-8 nm
The atomic number of the element with maximum number of unpaired electrons is:
  • 26
  • 33
  • 23
  • 15
The orbital angular momentum of 2p electron is:
  • zero
  • 3h
  • 6h
  • (2h)/(2n)
Proton bombardment of Th230 followed by emission of two alpha particles produces:
  • Ra223
  • Rn232
  • Fr222
  • Fr223
0 h : 0 m : 1 s

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