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Chemistry Grade 9 Unit 3: STRUCTURE OF THE ATOM

national exam questions have come from this unit. It runs 64 pages; one careful study pass takes about 6.7 hours, and its difficulty is easier among Chemistry units. Each section below lists the questions set from it, with the year, and opens the page that teaches it.

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3.1 Historical Development of the Atomic Theories of Matter · read p. 52
Not asked in a national paper yet.
3.2 Fundamental Laws of Chemical Reactions · read p. 56
  • 2017 E.C., Q21 – Which of the following statements CORRECTLY describes the law of conservation of mass?
  • 2016 E.C., Q54 – A student added 25 mL of AgNO 3 solution to a beaker and weighed the mass of the beaker and its content as m 1 . He/she added 50 mL of a saturated solution of NaCl into the second beaker and weighed the mass of the beake
  • 2015 E.C., Q35 – Carbon forms two stable compounds with oxygen, namely, carbon monoxide and carbon dioxide. For a fixed mass of carbon, the ratio of oxygen in carbon monoxide to oxygen in carbon dioxide is 1:2. This result is consistent
3.3 Atomic Theory · read p. 64
  • 2014 E.C., Q18 – Which of the following postulates of Dalton's atomic theory was modified by the modern atomic theory?
3.4 Discoveries of Fundamental Subatomic Particles and the Atomic Nucleus · read p. 69
  • 2018 E.C., Q11 – Many classic experiments have given indirect evidence about the nature of the atom. Which statement below is NOT correct about the results of these experiments?
  • 2017 E.C., Q69 – Which statement below CORRECTLY describes the Bohr's model of an atom?
  • 2014 E.C., Q31 – Which of the following is NOT true about cathode rays? Cathode rays
  • 2014 E.C., Q19 – Which of the following includes all of the known atomic models?
  • 2011 E.C., Q1 – What aspect of the modern view of atomic structure was proved by Rutherford's gold foil experiment?
  • 2009 E.C., Q13 – Which of the following particle was discovered by the cathode rays experiment?
  • 2008 E.C., Q32 – What new concept did Bohr adapt and use to formulate his made of the atom?
3.5 Composition of an Atom and the Isotopes · read p. 85
  • 2018 E.C., Q1 – Which of the following sub atomic particle is used to determine chemical properties of elements?
  • 2018 E.C., Q2 – An element has two isotopes with masses of 62.93 amu (69.17%) and 64.93 amu (30.83%). What is the average atomic mass?
  • 2017 E.C., Q28 – Silver has two known isotopes, Ag and Ag with their percent abundance of 52% and 48%, respectively. What is the average atomic mass of silver?
  • 2017 E.C., Q68 – Which one of the following CORRECTLY shows the relative charges of an electron, proton and neutron, respectively?
  • 2016 E.C., Q34 – Given the symbols of the three subatomic particles; electrons (e - ), protons (p + ) and neutrons (n 0 ), which of the following is the CORRECT comparison of the absolute masses of protons, electrons and neutrons?
  • 2015 E.C., Q45 – A nuclear breakdown in which particles or electromagnetic radiation is emitted is _______________.
  • 2015 E.C., Q30 – Which one of the following IS TRUE about isotopes?
  • 2013 E.C., Q64 – Which of the following is true about isotopes? Isotopes of an element have
  • 2012 E.C., Q30 – Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is that
  • 2010 E.C., Q4 – Who used the cathode Ray tube to discover the electron and determine its charge to mass ratio?