| Questions |
Answer |
Explanation |
|
1 Which of these phrases best describes
an atom?
(1) a positive nucleus surrounded by a
hard negative
shell
(2) a positive nucleus surrounded by a
cloud of negative
charges
(3) a hard sphere with positive
particles uniformly embedded
(4) a hard sphere with negative
particles uniformly embedded |
2 |
nucleus is positive
and the negative electrons are somewhere in the cloud
outside this nucleus |
|
2 Which statement is true about a proton
and an electron?
(1) They have the same masses and the
same charges.
(2) They have the same masses and
different charges.
(3) They have different masses and the
same charges.
(4) They have different masses and
different charges. |
4 |
protons and neutrons
have the same mass
electrons are 1/1836 of a
proton in mass
proton + ;electron - ;neutron
no charge |
|
3 The atomic mass
of an element is the weighted average of the masses of
(1) its two most abundant isotopes
(2) its two least abundant isotopes
(3) all of its naturally occurring
isotopes
(4) all of its radioactive isotopes
|
3 |
DEFINITION OF AN
ISOTOPE
all the isotopes |
|
4 What determines the order of placement
of the elements
on the modern Periodic Table?
(1) atomic number
(2) atomic mass
(3) the number of neutrons, only
(4) the number of neutrons and protons
|
1 |
PT base on atomic
numbers |
|
5 Which compound contains only covalent
bonds?
(1) NaOH
(3) Ca(OH) 2
(2) Ba(OH) 2
(4) CH3OH
|
4 |
Look for all
nonmetals (usually an organic compound) |
|
6 At 298 K, oxygen (O 2)
and ozone (O3)
have different
properties because their
(1) atoms have different atomic numbers
(2) atoms have different atomic masses
(3) molecules have different molecular
structures
(4) molecules have different average
kinetic energies
|
3 |
different numbers of
atoms = different structures |
|
7 Which substance represents a compound?
(1)
C(s)
(3) CO(g)
(2)
Co(s)
(4) O 2(g) |
3 |
two Capital
lettersCompounds are made of 2 or more different
elements |
|
8 All chemical reactions have a
conservation of
(1) mass, only
(2) mass and charge, only
(3) charge and energy, only
(4) mass, charge, and energy |
4 |
everything should be
conserved in a reaction |
|
9 Which characteristic is a property of
molecular substances?
(1) good heat conductivity
(2) good electrical conductivity
(3) low melting point
(4) high melting point
|
3 |
molecular is
referring to a covalent compound
low MP & BP, poor
conductors of heat and electricity,
nonelectrolytes, brittle |
|
10 Given the Lewis electron-dot diagram:
Which electrons are represented by all of the dots?
(1) the carbon valence electrons, only
(2) the hydrogen valence electrons, only
(3) the carbon and hydrogen valence electrons
(4) all of the carbon and hydrogen electrons |
3 |
dots represent
valence electrons that each atom brings into the bond |