1) Elements are different from compounds in that
a) elements can be broken down but compounds cannot
b) compounds can be broken down chemically but elements cannot
c) elements can contain oxygen but compounds cannot
d) none of the above
2) What distinguishes an atom from another?
a) size of the atom
b) size of the electrons
c) number of neutrons in the atom
d) number of protons in the atom
3) When an atom loses an electron or gains an electron, it becomes
a) an ion
b) a molecule
c) a compound
d) electrically neutral
4) At the molecular level, the distinction between solids, liquids, and gases at room temperature is attributed to
a) the speed of the molecules
b) the number of electrons in the molecule
c) the strength of the forces between molecules
d) the mass of the constituent molecule
5) In an electrically neutral atom, the number of protons is balanced by equal number o
a. neutrons
b. Electrons
c. Positrons
d. molecules
6) Which of the following is not a compound?
a) air
b) salt
c) ammonia
d) ....they are all compounds
Reasoning: Air is a mixture of N2, O2, and H2O, CO2. These molecules do not form chemical bonds with each other.
6) Which is the smallest particle of the ones listed below?
a) a molecule
b) a proton
c) an atom
d) a nucleus
7) Which of the forces determine the chemical properties of an atom?
a) friction force
b) electrical force
c) nuclear force
d) gravitational force
8) A molecule is
a) the same as the isotopes of an atom
b) a group of protons held together by nuclear forces
c) a group of chemical compounds held together by chemical bonds
d) a group of atoms held together by chemical bonds
9) A metal block has a density of 5000 kg/m3 and a volume of 2 m3. What is the block's mass?
a) 1000 kg
b) 10000 kg
c) 2500 kg
d) 5000 kg
10) Water has its maximum density at
a) 4o C
b) 10o C
c) 0o C
d) 100o C
11) A pure substance that cannot be decomposed by chemical means is
a) a molecule
b) a compound
c) an element
d) a solution
12) An ion can be
a) an atom with excess electrons
b) an atom with deficiency of electrons
c) all of the above
13) Which one has a larger density, a gold brick or a gold coin?
a) brick
b) coin
c) they both have the sme density
d) either, depending on their masses
14) Silver has a density of 10.5 g/cm3. What is the density of silver in kg/m3 ?
a) 10.5
b) 105
c) 1050
d) 10500
15) Which one of the followings is a mixture?
a) Copper
b) air
c) water
d) salt
Reasoning: Copper is an element. Water and salt are compounds.
16) The density of ice is about 930 kg/m3. How much is its density in g/cm3?
a) 0.93 g/cm3
b) 0.093 g/cm3
c) 9.3 g/cm3
d) 930 g/cm3
17) Magnesium and sodium are both metals, but magnesium has a much higher melting point. This is because
a) magnesium is a molecular solid
b) magnesium has stronger bonds than sodium
c) sodium has stronger bonds than magnesium
d) sodium has more electrons than magnesium
18) The reason that ice is less dense than the water is that when water freezes
a) its mass increases
b) its volume decreases
c) its mass decreases
d) its volume increases
19) Diamond and graphite are both carbon.They have different properties because
a) they have different atomic structure
b) they are made up of different substances
c) graphite has covalent bonds and diamond has ionic bonds
d) carbon atoms in graphite are different from carbon atoms in diamond
20) You see the symbol "CO" in a newpaper article. This symbol means
a) one atom of cobalt
b) one atom of copper
c) one atom of carbon and one atom of oxygen
d) one atom of copper and one atom of oxygen
21) How many elements are found naturally on the earth in significant quantities?
a) 81
b) 89
c) 103
d) 109
22) If a carbon atom loses a proton, a neutron, and an electron, what would it be then? An atom of
a) Carbon
b) Nitrogen
c) Boron
d) Beryllium
Reasoning: Carbon has 6 protons. Removing one protons leaves it with 5 and it no longer is Carbon. It is an isotope of Boron.
23) The periodic table was formulated by
a) Einstein
b) Dalton
c) Thomson
d) Mandeleev
24) Are most elements in the periodic table metallic or nonmetallic?
a. metallic
b. nonmetallic
25) Identify the period and the group in the periodic table for the element Bromine.
a) period 4, group 17
b) period 3, group 15
c) period 1, group 1
d) period 2, group 19