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CEM 141 MSU Final Exam Questions And Answers Rated A+ New Update Assured Satisfaction
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CEM 141 MSU Final ExamAmmonia reacts with oxygen to produce nitric oxide in water. Balance the equation using small,
whole number coefficients:
______ NH3 + ______ O2 --> ______ NO + ______ H2O
What is the coefficient for oxygen (O2)? - ANS-5
An MRI machine operates at a frequency of 30 kilohertz (kHz), what wavelength radiation does
this correspond to?
a. 1x10^10 m
b. 1x10^7 m
c. 1x10^5 m
d. 1x10^4 m - ANS-1x10^4 m
At room temperature, substance A is a solid and substance B is a gas. A and B react according
to the following equation:
A +3B --> C
At room temperature, what state of matter do you predict for substance C?
a. Solid, because C is heavier than A or B
b. Gas, because C is three parts B (which is a gas) and one part A (which is a solid).
c. Liquid, because C will be intermediate between a solid and a gas.
d. We cannot predict the state of matter because we don't know about the bonding/interactions
present within C. - ANS-We cannot predict the state of matter because we don't know about the
bonding/interactions present within C.
Atomic radius _______________ from left to right across a row on the periodic table.
I. Increases
II. Decreases
Because:
III. The number of electrons increases
IV. The mass increases
V. The relative attraction between the protons and the outer electrons increases. -
ANS-Decreases because the relative attraction between the protons and the outer electrons
increases
Boron nitride is the second hardest substance known (next to diamond). It has a very high
melting point but does not conduct electricity. What types of bonding do you think is present in
boron nitride?
a. There is covalent bonding within two-dimensional layers of alternating boron and nitrogen
molecules, with London dispersion forces between the layers.
, b. There is covalent bonding within boron nitride molecules (BN), and LDFs between the
molecules.
c. There is a three dimensional network of metallic bonds between boron and nitrogen atoms.
d. There are covalent bonds between boron and nitrogen atoms which exist in 3D network.
e. It is not possible to predict the type of bonding from a consideration of bulk properties. -
ANS-There are covalent bonds between boron and nitrogen atoms which exist in a 3D network.
Carbon can exist in many forms known as allotropes. Two such allotropes are diamond and
graphite. Unlike diamond, graphite conducts electricity. This is because:
a. In graphite, there are hybrid orbitals used for bonding that contain electrons.
b. In diamond, all of the electrons are in sigma bonds, which allows conductivity of electricity.
c. In graphite, there are unhybridized p-orbitals that extend over the entire sheet forming a
delocalized pi bonding network where electrons are free to move.
d. In diamond, the bonding electrons have enough energy and can therefore conduct electricity.
- ANS-In graphite, there are unhybridized p-orbitals that extend over the entire sheet forming a
delocalized pi bonding network where electrons are free to move.
Consider K+ and Cl-. Which do you predict is larger and why?
a. K+ is larger because potassium (K) is farther to the left and further down the table than
chlorine (Cl).
b. K+ is larger because it contains more electrons so there are more electron-electron
repulsions
c. K+ and Cl- are the same size because they both contain the same number of electrons so
there is the same amount of electron-electron repulsion.
d. Cl- is larger because anions are always larger than cations.
e. Cl- is larger because fewer protons are attracting the same number of electrons as in K+ -
ANS-Cl- is larger because fewer protons are attracting the same number of electrons as in K+
Consider the following statement: "A nitrogen molecule is made up of the same type of atoms."
Is this statement true or false and why?
I. True
II. False
III. An element is made up of one type of atom. Nitrogen is an element that exists as diatomic
molecules.
IV. Nitrogen is a compound that exists as diatomic molecules. Compounds are made of different
types of atoms.
V. Nitrogen is an element and therefore must exist as separate atoms and not molecules. -
ANS-True because an element is made up of one type of atom. Nitrogen is an element that
exists as diatomic molecules.
Consider the question: Is there an attractive force between a pencil and the earth?
Is this a scientific question? [Yes or No]
Because
III. It can be tested and answered through observations and experiments
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