AnswersBCHS KY-Chemistry Section ASolids and Plasmas

Solids and Plasmas — Cumulative exam Answers

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Which is true about reaction rates?

A
High reaction rates occur only in spontaneous reactions.
B
Low reaction rates occur only in nonspontaneous reactions.
C
Reaction rates are not dependent on high or low activation energies.
D
Reaction rates are not related to spontaneity.
2
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A scientist is examining a mixture of nitrogen, hydrogen, and ammonia. The individual pressures that are exerted by nitrogen and hydrogen are 0.26 atm and 0.28 atm, respectively. If the total pressure is 0.90 atm, what is the partial pressure of ammonia?Use .

Question illustration
A
0.27 atm
B
0.36 atm
C
0.54 atm
D
0.90 atm
3

Which of the following observations would indicate that a material is a pure substance?

A
It does not dissolve in water.
B
It changes color after heating.
C
It cannot be physically broken down into different types of atoms.
D
It can be physically broken down into different types of molecules.
4

Which is a component of John Dalton’s atomic theory?

A
The ratio of atoms in a compound can vary.
B
The atoms of a single element differ.
C
An atom is a small particle that cannot be broken down.
D
Atoms of different elements can be identical.
5

Consider the equation for the formation of water.2H2 + O2 2H2OWhat is the theoretical yield of H2O if 130 g of H2O is produced from 18 g of H2 and an excess of O2?

Question illustration
A
18 g
B
81 g
C
130 g
D
160 g
6

Which is a property of covalent compounds?

A
They ionize in solution.
B
They tend to be very hard.
C
They have a low boiling point.
D
They have a high melting point.
7

Which physical method can separate a mixture of steel ball bearings and marbles?

A
boiling
B
evaporation
C
filtration
D
sorting
8

How are isotopes defined?

A
forms of different elements that have the same number of neutrons in each atom
B
forms of different elements that have the same number of protons in each atom
C
forms of the same element that differ in the number of neutrons in each atom
D
forms of the same element that differ in the number of protons in each atom
9

The diagrams show gases that are stored in two separate but similar containers.If both gases are at the same temperature, which one has the greater pressure?

Question illustration
A
gas 1 because the particles are moving much faster
B
gas 1 because it has fewer particles that are close together
C
gas 2 because it has more particles that are colliding
D
gas 2 because the particles have more space between them
10

Which statement describes a limitation of the kinetic-molecular theory for a gas?

A
The theory assumes that particles do not experience intermolecular forces.
B
The theory states that pressure is inversely proportional to volume.
C
The theory assumes that particles are in random and continuous motion.
D
The theory states that pressure increases with temperature.
11

What is a three-dimensional structure that represents the alternating pattern of particles in a crystal?

A
a polyatomic ion
B
a crystal lattice
C
a covalent bond
D
a formula unit
12

Which of these properties is the best one to use for identification of an element?

A
the number of neutrons in the atomic nucleus
B
the number of protons in the atomic nucleus
C
the number of isotopes that are formed by the element
D
the number of charges on ions of the element
13

Based on its location in the periodic table, what can most likely be predicted about sulfur?

A
It has four valence electrons available for bonding.
B
It has four nonbonding electrons.
C
It has six valence electrons available for bonding.
D
It has six nonbonding electrons.
14

How does an increase in reactant concentration affect the rate of reaction?

A
It leads to more frequent collisions, which increase reaction rate.
B
It leads to less frequent collisions, which increase reaction rate.
C
It leads to more frequent collisions, which decrease reaction rate.
D
It leads to less frequent collisions, which decrease reaction rate.
15

Which statement best compares the melting point of butane (C4H10) with that of octane (C8H18)?

A
The melting points of both substances are identical.
B
The melting point is higher for butane.
C
The melting point is higher for octane.
D
The comparison of melting points cannot be made.
16

According to Le Chatelier’s principle, a change in pressure affects the chemical equilibrium of the reaction system under what condition?

A
The reactants and the products are in the solid phase.
B
The reactants and the products are in the liquid phase.
C
Some of the reactants or the products are in the gaseous phase.
D
Some of the reactants or the products are solid, and some are liquid.
17

Which compound most likely contains polar covalent bonds?

A
NaCl
B
AlF3
C
Br2
D
NF3
18

Which statement best describes the light that will cause emission of electrons from a given metal through the photoelectric effect?

A
light with a low enough intensity
B
light with a high enough frequency
C
light with a high enough intensity
D
light with a low enough frequency
19

Which quantity is held constant when working with Boyle’s, Charles’s, and Gay-Lussac’s laws?

A
volume
B
moles
C
pressure
D
temperature
20

Consider the substances below.• 1 mol of beryllium• 1 mol of salt• 1 mol of water• 1 mol of hydrogenWhich statement is true about these substances?

A
They have exactly the same mass.
B
They have different numbers of particles.
C
They have the same number of atoms.
D
They have different masses.

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