304k exam 1-solutions

Version 1437 – 304K Exam 1 – sutcliffe – (52230) 1

This print-out should have 20 questions.Multiple-choice questions may continue onthe next column or page – find all choicesbefore answering.

001 10.0 points

Which scientist is associated with the discov-ery of the electron?

1. Dalton

2. Thomson correct

3. Rutherford

4. Bohr

5. Millikan

Explanation:

J.J. Thomson studied the deflection of cath-ode rays in different electric and magneticfields to obtain the electron’s charge-to-massratio. This ratio is constant even when differ-ent gases, electrodes, and power sources areused, indicating that electrons are fundamen-tal particles present in all atoms.

002 10.0 points

Which region of the atmosphere is the high-est?

1. troposphere

2. hemisphere

3. mesosphere correct

4. stratosphere

Explanation:

003 10.0 points

If you have 7 molecules of SO2 gas in1.317× 105 molecules of air, what is the con-centration of SO2 in parts per million?

1. 7 ppm

2. 28 ppm

3. 53.1511 ppm correct

4. 7× 10−6 ppm

5. 5.31511× 10−5 ppm

6. 14 ppm

Explanation:

nSO2= 7 molec nair = 1.317× 105 molec

Set up a ratio to solve for how manymolecules of SO2 there are in 106 molecules ofair:

7 molec SO2

1.317× 105 molec air=

? molec SO2

106 molec air

? molec SO2 =7 molec SO2

1.317× 105 molec air

× 106 molec air

= 53.1511 ppm

004 10.0 points

The second most abundant component of dryair is

1. carbon dioxide.

2. oxygen. correct

3. argon.

4. nitrogen.

Explanation:

005 10.0 points

Which of the big four pollutants is NOT arespiratory irritant?

1. O2

2. CO correct

3. SOx

4. NOx

5. O3


Explanation:

006 10.0 points

Of the following combinations of compoundsand names, the one which is incorrect is

1. LiBr : lithium bromide

2. N2O5 : dinitrogen pentoxide

3. SO2 : sulfur dioxide

4. K2S : dipotassium sulfide correct

5. Cu2O : copper(I) oxide

Explanation:

The potassium ion is K+; the sulfide ion isS2−. Two K+ are needed to balance the eachS2−, so the formula K2S is correct. This is anionic compound and prefixes are not neededto name it. It should be correctly namedpotassium sulfide.SO2 and N2O5 are both covalent com-

pounds and are named correctly using theappropriate prefixes.The copper(I) ion is Cu+; the oxide ion is

O2−. Two Cu+ are needed to balance thecharge of each O2−, so the formula is Cu2O iscorrect.The lithium ion is Li+; the bromide ion is

Br−. One Br− is needed to balance the chargeof each Li+, so the formula LiBr is correct.

007 10.0 points

Which isotope has 35 protons, 35 electrons,and 46 neutrons?

1. 8135Br correct

2. 4635Br

3. 8146Pd

4. 3546Pd

Explanation:

The standard nuclide symbol takes the formof A

ZE were E is the element symbol, A is themass number (number p+ + number n), and

Z is the atomic number (number p+). Anisotope with 35 protons (p+) and 46 neutrons(n) has an atomic number of 35 and a massnumber of 35 p+ + 46n = 81 amu. Br has anatomic number of 35, so the isotope is 81

35Br.

008 10.0 points

Which of the following statements is true re-garding electromagnetic radiation?

1. Electromagnetic radiation with a wave-length of 400 nm has a frequency that is lowerthan that with a wavelength of 600 nm.

2. Electromagnetic radiation with a wave-length of 600 nm travels faster than that witha wavelength of 400 nm.

3. Electromagnetic radiation with a wave-length of 600 nm has a frequency that is lowerthan that with a wavelength of 400 nm. cor-rect

4. Electromagnetic radiation with a wave-length of 400 nm travels faster than that witha wavelength of 600 nm.

5. The frequency of electromagnetic radia-tion determines how fast it travels.

Explanation:

v = f λ, so λ =1

f. Higher wavelengths cor-

respond to lower frequencies, and vice versa.

009 10.0 points

Depict the electron configuration for siliconusing rare gas (shorthand) notation.

1. [Ne] 3s2 3p4

2. [Ne] 3p2

3. [Ne] 3s2 3p2 correct

4. 1s2 2s2 2p6 3s2 3p2

Explanation:

Use either the periodic table method or thepyramid method to solve.


010 10.0 points

Hint: this substance is colored.An essential ingredient in the production of

photochemical smog is

1. nitrogen dioxide. correct

2. carbon monoxide.

3. carbon dioxide.

4. hydrogen sulfide.

5. sulfur dioxide.

Explanation:

Atmospheric oxygen is oxidized by NO2

which dissolves in water vapor in the air, pro-ducing nitric acid.

N2 + 2O2 → 2NO2

NO2 +H2O → 2HNO3

011 10.0 points

Which of the following electron configurationswould represent an alkaline earth metal?

1. [Ne] 3s2 3p5

2. [Ar] 3d5 4s2

3. [Ne] 3s2 correct

4. [He] 2s2 2p3

5. [Ar] 4s1

Explanation:

012 10.0 points

013 10.0 points

Which part of risk assessment is most diffi-cult to determine and thus, most debated?

1. Concentration2. Toxicity CORRECT3. Duration4. Exposure

Explanation:

Exposure is least contentious: it is foundby measuring concentration of a given pol-lutant (via a calibrated gas sensor) and theduration of exposure. Toxicity is more diffi-cult to determine: Testing on human subjectsis obviously not acceptable and animal mod-els may not fully approximate and have theirown ethical dilemmas.

014 10.0 points

What is the density of a wood block that hasa mass of 97.5 g and measures 12 cm × 3.33cm × 4.2 cm? (Use significant digits.)

1. 0.58 g/cm3 correct

2. 1.723538 g/cm3

3. 0.5809381 g/cm3

4. 0.581 g/cm3


5. 1.72 g/cm3

Explanation:

015 10.0 points

Which of the following is NOT produced fromburning gasoline?

1. SO2 correct

2. CO

3. VOCs

4. NO2

5. More than one of these

6. CO2

Explanation:

Since there is little to no sulfur in gasoline,SO2 is not produced from burning gasoline.The other molecules listed are produced. TheCO, CO2, and VOCs come from gasoline’sreacting with air during combustion and in-complete combustion. The nitrogen in NO2

comes from the air (78% nitrogen) engagingin the combustion of gasoline at high temper-atures.

016 10.0 points

Balance the equation

?HBr+?Fe(OH)3 → ? FeBr3+?H2O

using the smallest possible integers. The sumof the coefficients is

1. 6.

2. 7.

3. 9.

4. 8. correct

Explanation:

A balanced equation must have the samenumber of each kind of atom on both sides

of the equation. We find the number of eachkind of atom using equation coefficients andcomposition stoichiometry. For example, wefind there are 6 H atoms on the product side:

?H atoms = 3H2O×

2H

1H2O= 6H

The balanced equation is

Fe(OH)3 + 3HBr → FeBr3 + 3H2O

and has 1 Fe, 6 H, 3 Br and 3 O atoms on eachside.? sum coefficients = 1 + 3 + 1 + 3 = 8.

017 10.0 points

Which of the following is a chemical change?

1. leaves changing colors in the fall correct

2. crushing a leaf in your hand

3. cutting grass

4. boiling water

Explanation:

A chemical change occurs when one or moresubstances are consumed (at least partially),and one or more new substances are formed.Leaves changing colors in the fall suggests

a chemical change as the pigments have un-dergone a change chemically.

018 10.0 points

Considering pollution of the atmosphere, ox-ides of nitrogen come predominately from

whereas oxides of sulfur come predomi-nately from .

1. internal combustion engines; power plantscorrect

2. petrochemical factories; internal combus-tion engines

3. nuclear power plants; petrochemical fac-tories


4. power plants; internal combustion en-gines

5. internal combustion engines; petrochemi-cal factories

6. petrochemical factories; nuclear powerplants

Explanation:

019 10.0 points

A young senator excited about Green Chem-istry presents new legislation to set controlson vehicles and industry to completely removeall pollutant molecules from the air. Which isthe best critique of this proposal?

1. This is a wonderful and attainable goalthat merely requires the proper incentives inorder to be realized.

2.While this sounds like a wonderful idea, itis not attainable regardless of regulations orincentives. correct

3. While this would be great in theory, ac-complishing it would require too much moneyand more government control than is appro-priate in a free market economy.

4. This is not a good plan because the U.S.should not have to concern itself with thischallenge unless all countries are willing tomake similar sacrifices.

Explanation:

Although we are now able to detect singlemolecules, we can only do this for really smallsamples, so we cannot be absolutely sure allpollutant molecules are removed. Some pollu-tants are also generated via natural processes(volcanoes, etc).

020 10.0 points

The lines in an atomic line emission spectrumare due to

1. the movement of electrons from higher

energy states to lower energy states in atoms.correct

2. the movement of electrons from lower en-ergy states to higher energy states in atoms.

3. the presence of isotopes.

4. nuclear transitions in atoms.

Explanation:

304k exam 1-solutions

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