Answers CR03101 ChemistryUnit Test

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Which expression is equal to the number of milliliters (mL) in 12.5 liters (L)?

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Which describes a step in the process of forming an ionic bond?

A metal atom loses electrons and becomes a positive ion.

A metal atom gains electrons and becomes a negative ion.

A nonmetal atom loses electrons and becomes a negative ion.

A nonmetal atom gains electrons and becomes a positive ion.

Which best describes why NH4+ can form an ionic bond with Cl–?

Its outermost shell gains one or more electrons from Cl–.

Its positive charge is attracted to the negative charge of Cl–.

It has a negative charge that is spread over the entire ion.

It has a nitrogen atom that is strongly attracted to Cl–.

Which represents the balanced nuclear equation for the beta plus decay of C-11?

Superscript 11 subscript 6 upper C right arrow superscript 11 subscript 5 upper B plus superscript 0 subscript plus 1 e.

Superscript 11 subscript 6 upper C right arrow superscript 11 subscript 7 upper N plus superscript 0 subscript plus 1 e.

Superscript 11 subscript 6 upper C right arrow superscript 11 subscript 7 upper N plus superscript 0 subscript negative 1 e.

Superscript 11 subscript 6 upper C right arrow superscript 11 subscript 5 upper B plus superscript 0 subscript negative 1 e.

Consider the three equations below.Which statement do these reactions best support?

Beta decay occurs only in certain atoms.

Alpha decay occurs only in certain atoms.

Chain reactions play important roles in the process of nuclear fission.

Nuclear fusion plays an important role in making elements that are heavier than helium.

Which statement describes mechanical energy?

the energy that is stored in chemical bonds

the energy that is associated with temperature

the sum of the kinetic energy and the potential energy of an object

the type of energy that is associated with electromagnetic radiation

Which defines the average kinetic energy of a system’s particles?

density

pressure

temperature

volume

A radioactive nuclide that is used for radiation therapy for cancer has 33 neutrons and a mass number of 60. Which is the correct symbol for this nuclide?

Superscript 27 subscript 60 upper C o.

Superscript 33 subscript 60 upper C o.

Superscript 60 subscript 33 upper C o.

Superscript 60 subscript 27 upper C o.

Which property would xenon most likely have?

It is stable.

It is a solid.

It is flammable.

It is silver in color.

Which equation is a decomposition reaction?

Li2CO3 Li2O + CO2

Zn + HCl ZnCl2 + H2

Na2O + CO2 Na2CO3

C6H12O6 + O2 CO2 + H2O

Which statement describes the law of conservation of energy?

All systems will exchange matter and energy with their surroundings.

All systems can exchange energy, but not matter, with their surroundings.

Energy cannot be created nor destroyed, but it changes from one form to another.

Energy is destroyed in most chemical reactions when new products are formed.

Which is true about reaction rates?

High reaction rates occur only in spontaneous reactions.

Low reaction rates occur only in nonspontaneous reactions.

Reaction rates are not dependent on high or low activation energies.

Reaction rates are not related to spontaneity.

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

It leads to more frequent collisions, which increase reaction rate.

It leads to less frequent collisions, which increase reaction rate.

It leads to more frequent collisions, which decrease reaction rate.

It leads to less frequent collisions, which decrease reaction rate.

The table below gives the data that is needed to calculate the average atomic mass of element B.IsotopeAtomic mass (amu)Relative abundance (%)B-1010.0119.91B-1111.0180.09Based on these data, what is the average atomic mass of element B?

10.01

10.51

10.81

11.01

An unbalanced chemical equation for the reaction of boron fluoride with lithium sulfite is shown below.BF3 + Li2SO3 B2(SO3)3 + LiFWhat is the coefficient of lithium fluoride in the balanced chemical reaction?

Which statement defines specific heat capacity for a given sample?

the temperature of a given sample

the temperature that a given sample can withstand

the quantity of heat that is required to raise the sample’s temperature by 1°C (Kelvin)

the quantity of heat that is required to raise 1 g of the sample by 1°C (Kelvin) at a constant pressure

In the diagram below, particles of the substance are moving from the liquid phase to the gas phase at the same rate as they move from the gas phase to the liquid phase.The gas and liquid are at

equilibrium.

a high vapor pressure.

a low vapor pressure.

zero vapor pressure.

A copper rod that has a mass of 200.0 g has an initial temperature of 20.0°C and is heated to 40.0°C. If 1,540 J of heat are needed to heat the rod, what is the specific heat of copper?Use .

0.0130 J/(gi°C)

0.0649 J/(gi°C)

0.193 J/(gi°C)

0.385 J/(gi°C)

If an unshielded sample of radioactive material emits alpha particles, what effect will it have on a person sitting in the next room? (Assume the wall between rooms is composed of concrete.)

None, because the wall will block the radiation.

The radiation will travel through the person’s body.

None, because the radiation will bounce off the person’s body.

The radiation will be totally absorbed by the person’s body.

Which element would most likely have chemical properties similar to that of magnesium (Mg)?

Which statement describes the electron sea model for metallic bonding?

This model involves electrons held tightly between atoms.

This model explains all properties of metals.

This model involves electrons moving among bands of orbitals.

This model is the simplest model.

Which statement best explains the change that occurs when gas particles move more slowly?

The temperature increases because the average kinetic energy decreases.

The temperature increases because the average kinetic energy increases.

The temperature decreases because the average kinetic energy decreases.

The temperature decreases because the average kinetic energy increases.

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

light with a low enough intensity

light with a high enough frequency

light with a high enough intensity

light with a low enough frequency

Which is a property of covalent compounds?

They ionize in solution.

They tend to be very hard.

They have a low boiling point.

They have a high melting point.

Chuck wants to know how many electrons in an atom are not paired up. Which model would be best for Chuck to write out?

a set of quantum numbers for the last electron in the atom

a configuration with numbers, letters, and superscripts

a dot structure of the atom

an orbital notation of the atom

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