Which of the following correctly represents the electronic distribution in the Mg atom?
  • 3, 8, 1
  • 2, 8, 2
  • 1, 8, 3
  • 8, 2, 2
Rutherford’s ‘alpha (α) particles scattering experiment’ resulted in the discovery of
  • electron
  • proton
  • nucleus in the atom
  • atomic mass
The number of electrons in an element X is 15 and the number of neutrons is Which of the following is the correct representation of the element?
  • \(_{15}^{31}\)X
  • \(_{16}^{31}\)X
  • \(_{15}^{16}\)X
  • \(_{16}^{15}\)X
The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is What is the number of electrons in the ion?
  • 13
  • 10
  • 14
  • 16
The first model of an atom was given by
  • N. Bohr
  • E. Goldstein
  • Rutherford
  • J. J. Thomson
An atom with 3 protons and 4 neutrons will have a valency of
  • 3
  • 7
  • 1
  • 4
Which of the following statement is always correct?
  • An atom has equal number of electrons and protons.
  • An atom has equal number of electrons and neutrons.
  • An atom has equal number of protons and neutrons.
  • An atom has equal number of electrons, protons and neutrons.
Hydrogen exists in three isotopic forms, \(_{1}^{1}\)H, \(_{1}^{2}\)H, \(_{1}^{3}\)H known as protium, deuterium and tritium. Why are all the isotopes neutral in nature?
  • Since neutrons are neutral in nature hence isotopes are electrically neutral.
  • All the isotopes have one electron and one proton, hence they are neutral.
  • All the isotopes have one proton and one neutron, hence they are neutral.
  • Increasing number of protons in the isotopes make them neutral.
How many electrons are present in M-shell of an element with atomic number 20?
  • 5
  • 8
  • 12
  • 18
There are two atomic species X and Y, such that
  • X and Y are isobars.
  • X and Y have different chemical properties.
  • X and Y have different physical properties.
  • All of these.
An alpha particle is also known as:
  • subatomic particle
  • an unionised helium atom
  • a neutral particle
  • a doubly-charged helium ion
There are three isotopes of carbon which are named as C-12, C-13 and C-14 out of which C-12 is the most abundant isotope. In the given structures of 3 isotopes, what will be the composition of the nucleus?
  • C-12 : 6p + 6n, C-13 : 7p + 6n, C-14 : 8p + 6n
  • C-12 : 6p + 6n, C-13 : 6p + 7n, C-14 : 6p + 8n
  • C-12 : 6p + 6n, C-13 : 5p + 8n, C-14 : 7p + 7n
  • C-12 : 6p + 6n, C-13 : 12p + 1n, C-14 : 5p + 9n
Which of the following isotope is used in the treatment of blood cancer?
  • P-32
  • I-131
  • Co-60
  • any of these
Isobars do not differ in the number of
  • protons
  • electrons
  • neutrons
  • nucleons
The maximum number of electrons that can be accommodated in third shell ( n = 3) is:
  • 10
  • 2
  • 18
  • 8
Which of the following have equal number of neutrons and protons?
  • Chlorine
  • Hydrogen
  • Fluorine
  • Deuterium
The nucleons are
  • None of these
  • Protons and neutrons
  • Neutrons and electrons
  • Protons and electrons
The nucleus of an atom contains:
  • Protons only
  • Neutrons
  • Protons and neutrons
  • Electrons only
Which of the following arrangements of electrons represent magnesium (Mg)?
  • 2, 8, 2
  • 2, 8, 3
  • 2, 8, 1
  • 2, 8, 4
The charge on an electron is:
  • 1.6 x 10-6 Coulombs
  • 1.6 x 10-20 Coulombs
  • 1.6 x 10-16 Coulombs
  • 1.6 x 10-19 Coulombs
Which of the following pairs are isotopes?
  • Ice and steam
  • Hydrogen and deuterium
  • Nitric oxide and nitrogen dioxide
  • Oxygen and ozone
Why was Thomson’s Model of an atom failed? i. It could not explain the screening of negative charges from that of positive ii. It did not tell about the presence of electrons iii. It did not give an idea about the discrete energy levels iv. It explained the atom as a whole to be electrically neutral Choose the correct option from the following:
  • Both (ii) & (iv)
  • Both (i) & (iii)
  • Only (iii)
  • Only (i)
What property of an element determines its chemical behavior?
  • Valency of an element
  • The molar mass of the element
  • Size of an element
  • None of these
The relative atomic masses of many elements are not whole numbers because:
  • The atoms ionize during the determination of their masses
  • They cannot be determined accurately
  • Presence of impurities
  • Existence of isotopes
Which f the following is not a basic particle of an element?
  • An atom
  • A molecule
  • An ion
  • None
The work function of a metal is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from the metal is approximately:
  • 540nm
  • 400 nm
  • 220 nm
  • 300 nm
The atomic number of an element is 11 ad its mass number isThe correct order representing the number of electrons, protons and neutrons respectively in this atom is:
  • 23, 11, 23
  • 11, 12, 11
  • 11, 11, 12
  • 12, 11, 11
What is an electron?
  • A wave
  • Either of two, depending on how it is observed
  • Neither of these
  • A particle
Which of the following has a charge of +1 and a mass of 1 amu?
  • An electron
  • A helium nucleus
  • A neutron
  • A proton
The isotopes of an element have:
  • Same mass number
  • The same number of neutrons
  • None of these
  • Same atomic number
0 h : 0 m : 1 s

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