Electrons whirl around the center of the atom at high speed, forming a(n)
A) spiral.
B) figure 8.
C) cylinder.
D) electron cloud.
E) helix.
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Question 2) The center of an atom is called the
A) core.
B) hub.
C) middle point.
D) nucleus.
E) focus.
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Question 3) A(n) ________ is a pure substance composed of atoms of only one kind.
A) element
B) macromolecule
C) ion
D) isotope
E) compound
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Question 4) If an element is composed of atoms with an atomic number of 6 and a mass number of 14, then a non-isotopic atom of this element contains
A) 6 protons.
B) 8 electrons.
C) 8 neutrons.
D) 6 protons and 8 electrons.
E) 6 protons and 8 neurons.
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Question 5) If an isotope of oxygen has 8 protons, 10 neutrons, and 8 electrons, its mass number is
A) 26.
B) 16.
C) 18.
D) 8.
E) 12.
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Question 6) Given the following approximate values, calculate the molecular weight for NaCl. Atomic number for Na: 11, Atomic weight for Na: 23 g/mol, Atomic number for Cl: 17,Atomic weight for Cl: 35 g/mol, Boiling point for Cl: -34 C
A) 11 g/mol
B) 28 g/mol
C) 34 g/mol
D) 40 g/mol
E) 58 g/mol
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Question 7) In any given molecule, the sum of the atomic weights of its component atoms is called
A) molecular mass.
B) molecular weight.
C) atomic mass.
D) atomic weight.
E) chemical mass.
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Question 8) By weight, which element is the second most abundant in the human body?
A) oxygen
B) carbon
C) hydrogen
D) nitrogen
E) calcium
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Question 9) Which element commonly has only a proton as its nucleus?
A) helium
B) neon
C) argon
D) hydrogen
E) carbon
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Question 10) Helium (HE) has an atomic number of 2. It is chemically stable because it
A) is neutral in electrical charge.
B) readily ionizes to react with other atoms.
C) has a full outer electron shell.
D) will form a covalent bond with another He atom.
E) lacks electrons, thus the He atom is stable.
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