Mechanical Engineering Unit 1 To 10 Hvacr Technician Takes Reading Which Type Gauge Using Impossible Tell Using Manometer

237)

An HVACR technician takes a reading of 25 in Hg. Which type of gauge is he using?

A)

It is impossible to tell.

B)

He is using a manometer.

C)

He is using a high–pressure gauge.

D)

He is using a compound gauge.

Answer:

D

Explanation:

A)

B)

C)

D)

238)

What units are used to measure vacuum?

A)

In negative psi (–psi)

B)

In reciprocal psi (1/psi)

C)

In inches of mercury

D)

In negative pascals (–p)

Answer:

C

Explanation:

A)

B)

C)

D)

239)

Convert a pressure of 10 psi to inches of mercury. How many inches of mercury is the pressure?

A)

15 inches of mercury

B)

100 inches of mercury

C)

20 inches of mercury

D)

50 inches of mercury

Answer:

C

Explanation:

A)

B)

C)

D)

240)

A refrigeration system was checked for leaks. The system temperature and surroundings were

75°F when the system was charged with nitrogen to 100 psig. The temperature then dropped to

50°F. What should the pressure be if no nitrogen has escaped?

A)

90 psig

B)

100 psig

C)

9 psig

D)

94 psig

Answer:

D

Explanation:

A)

B)

C)

D)

241)

What is the conversion of 20 inches of mercury to psi?

A)

60 psi

B)

10 psi

C)

40 psi

D)

2 psi

Answer:

B

Explanation:

A)

B)

C)

D)

61

242)

What is the pressure in psi required to lift water 20 feet?

A)

20 ft × 0.433 lb/ft = 8.66 psi

B)

14.7 psijust enough to overcome atmospheric pressure

C)

(20 ft × 0.433 lb/ft) 144 in2/ft2= 0.06 psi

D)

It is not possible to determine the pressure without knowing the cross sectional area of the

pipe.

Answer:

A

Explanation:

A)

B)

C)

D)

243)

When gas exerts pressure on its container, the pressure is:

A)

Distributed equally on all surfaces of the container.

B)

Higher at corners and converging surfaces.

C)

Higher near the middle of the container than toward the outside.

D)

Higher on the larger surfaces.

Answer:

A

Explanation:

A)

B)

C)

D)

244)

Atmospheric pressure is affected by:

A)

Altitude, temperature, and humidity.

B)

Altitude and temperature.

C)

Magnetic pole location, altitude, and temperature.

D)

Humidity, temperature, and geosynchronous location.

Answer:

A

Explanation:

A)

B)

C)

D)

245)

Define a vacuum.

A)

A vacuum is a negative pressure.

B)

Vacuum is the reciprocal of pressure. For every pressure there is a reciprocal vacuum.

C)

A vacuum is any pressure less than atmospheric pressure.

D)

A vacuum is anti–pressure created by counterclockwise molecular rotation.

Answer:

C

Explanation:

A)

B)

C)

D)

62

246)

Standard atmospheric pressure at sea level with a temperature of 59°F is:

A)

14.7 psia or 29.92 in Hg.

B)

29.92 psig or 14.7 psia.

C)

14.7 psig or 29.92 in Hg.

D)

29.92 psia or 14.7 in Hg.

Answer:

A

Explanation:

A)

B)

C)

D)

247)

How should accidents be reported to the company office?

A)

A privacy report form should be filled out and turned into the company office.

B)

A medical report form should be filled out and turned into the company office.

C)

A progress report form should be filled out and turned into the company office.

D)

An accident report form should be filled out and turned into the company office.

Answer:

D

Explanation:

A)

B)

C)

D)

248)

The maximum fill level for a refillable refrigerant cylinder is:

A)

100% of its volume if the cylinder is rated for that particular refrigerant.

B)

70% of its volume.

C)

Refillable cylinders should not be refilled with refrigerant.

D)

80% of its volume.

Answer:

D

Explanation:

A)

B)

C)

D)

249)

What class fire extinguisher should be used to safely extinguish a flammable liquid?

A)

Class A

B)

Class D

C)

Class B

D)

Class C

Answer:

C

Explanation:

A)

B)

C)

D)

63

250)

When should you read the SDS for a particular chemical product?

A)

After completing the job

B)

Before using the product

C)

In the event of any injury causing accidents

D)

Immediately after exposure to the product

Answer:

B

Explanation:

A)

B)

C)

D)

251)

A refrigerant container should never be heated or stored in temperatures above:

A)

125°F.

B)

95°F.

C)

115°F.

D)

100°F.

Answer:

A

Explanation:

A)

B)

C)

D)

252)

Information that is required on a SDS includes which of the following? (You may select more than

one.)

A)

Instructions for use

B)

Flammability

C)

Physical and chemical properties

D)

Hazardous ingredients

E)

Emergency contact information

F)

Identity of the chemical

G)

Manufacturing date

Answer:

B, C, D, E, F

Explanation:

A)

B)

C)

D)

E)

F)

G)

64

253)

Select the lifting techniques that will reduce the possibility of injury from lifting a heavy item.

(You may select more than one.)

A)

Use your back muscles to do the work.

B)

Lift quickly.

C)

Use your leg muscles to do the work.

D)

Keep the load close to your body.

E)

Lift slowly.

F)

Keep your knees as straight as possible.

G)

Keep your back as straight as possible.

Answer:

C, D, E, G

Explanation:

A)

B)

C)

D)

E)

F)

G)

254)

While materials that contain asbestos are processed, shaped, or cut:

A)

An exhaust blower system using a 50% efficient filter must be operating.

B)

An exhaust blower system using a 7% efficient filter must be operating.

C)

An exhaust blower system using a HEPA filter must be operating.

D)

An exhaust blower system using a 5% efficient filter must be operating.

Answer:

C

Explanation:

A)

B)

C)

D)

255)

Acetylene should never be used:

A)

Above 20 psi.

B)

Above 15 psi.

C)

Below 20 psi.

D)

Below 15 psi.

Answer:

B

Explanation:

A)

B)

C)

D)

65

256)

When working in a confined space where concentrations of harmful substances are very high,

why should atmosphere–supplying respirators be worn?

A)

To purify air of harmful dust, mist, metal, fumes, and vapors

B)

To enable asphyxiation to occur in a very short time

C)

To circulate odorless, tasteless, invisible refrigerants

D)

To supply clean breathing air from a compressed air source

Answer:

D

Explanation:

A)

B)

C)

D)

257)

When working with tools, a safety procedure to follow is to:

A)

Check where the tool was manufactured regarding quality.

B)

Make sure the tools belong to you.

C)

Always read the manufacturer’s instructions.

D)

Read the warranty information.

Answer:

C

Explanation:

A)

B)

C)

D)

258)

How can maintaining an orderly shop be beneficial?

A)

Less time is spent using required tools or materials.

B)

Less time is wasted searching for required tools or materials.

C)

There is more frustration when searching for required tools or materials.

D)

There is less productivity when using required tools or materials.

Answer:

B

Explanation:

A)

B)

C)

D)

259)

A simple tool that technicians can use to check for energized circuits is a:

A)

Digital storage oscilloscope.

B)

Noncontact voltage detector.

C)

Screwdriver with a good insulated handle.

D)

Wattmeter.

Answer:

B

Explanation:

A)

B)

C)

D)

66

260)

Select the gases that are safe to use for refrigeration system pressure testing. (You may select more

than one.)

A)

Acetylene

B)

Oxygen

C)

Nitrogen

D)

Carbon dioxide

Answer:

C, D

Explanation:

A)

B)

C)

D)

261)

The top of an extension ladder:

A)

At least 12 inches below the point where it rests on the building.

B)

Flush with the edge of the roof.

C)

Should extend at least 36 inches above the point where it rests on the building.

D)

At least 12 inches above the point where it rests on the building.

Answer:

C

Explanation:

A)

B)

C)

D)

262)

How can a nontoxic, nonflammable refrigerant still be dangerous when released in a confined

space?

A)

A chemical reaction with the air can create a flammable byproduct.

B)

The refrigerant can replace the air, causing suffocation.

C)

The space temperature can quickly drop below freezing.

D)

A chemical reaction with the air can create a toxic gas.

Answer:

B

Explanation:

A)

B)

C)

D)

263)

The calculations for density and specific gravity for Systems International (SI) are:

A)

Inversely proportional when compared with AHRI standard conditions.

B)

Reciprocal values of ACCA standard conditions.

C)

Reciprocal values of ANSI standard conditions.

D)

The same as AHRI standard conditions using metric values.

Answer:

D

Explanation:

A)

B)

C)

D)

67

264)

The density of a gas that occupies 30 cubic feet and weighs 3 pounds is:

A)

Density = 3 lb × 30 ft3= 900 lb/ft3.

B)

Density = 30 ft3+ 3 lb = 33 lb/ft.3.

C)

Density = 3 lb/30 ft3= 0.1 lb/ft 3.

D)

Density = 30 ft3/3 lb = 10 ft3/lb.

Answer:

C

Explanation:

A)

B)

C)

D)

265)

The outdoor ambient temperature for AHRI rating condition “A” is:

A)

75°F.

B)

95°F.

C)

70°F.

D)

85°F.

Answer:

B

Explanation:

A)

B)

C)

D)

266)

The evaporation process occurs when:

A)

A liquid has reached critical mass.

B)

A liquid is above its critical temperature.

C)

A liquid is below its critical pressure.

D)

A liquid is below its boiling point.

Answer:

D

Explanation:

A)

B)

C)

D)

267)

Protons have a ________ charge.

A)

positive

B)

centrifugal

C)

negative

D)

kinetic

Answer:

A

Explanation:

A)

B)

C)

D)

68

268)

Properties of matter that determine how chemicals react to one another:

A)

Are tested in pressures above atmospheric.

B)

Are tested in pressures below atmospheric.

C)

Are known as chemical properties of matter.

D)

Are known as physical properties of matter.

Answer:

C

Explanation:

A)

B)

C)

D)

269)

When calculating the specific gravity of gas, the substance used as the comparative constant in the

formula is:

A)

Oxygen.

B)

Air.

C)

Nitrogen.

D)

Natural gas.

Answer:

B

Explanation:

A)

B)

C)

D)

270)

Define triple point.

A)

The pressure and temperature where a solid and a liquid have the same properties

B)

The pressure and temperature above which a substance will cease to exist

C)

The pressure and temperature at which gas and liquid have the same properties

D)

The pressure and temperature where a substance can exist simultaneously as a solid, a

liquid, and a gas in thermal equilibrium

Answer:

D

Explanation:

A)

B)

C)

D)

271)

A person riding in a car flies forward when the car comes to a sudden stop. What concept does

this illustrate?

A)

Weight

B)

Calibration

C)

Mass

D)

Inertia

Answer:

D

Explanation:

A)

B)

C)

D)

69

272)

Matter cannot be created or destroyed, but it can and does change form. This statement is known

as:

A)

Dalton’s law of matter and energy.

B)

The second law of thermodynamics.

C)

The law of conservation of matter.

D)

Charles’ law of kinetic energy.

Answer:

C

Explanation:

A)

B)

C)

D)

273)

When a liquid boils:

A)

Its temperature is always 212°F.

B)

It is releasing heat while changing from liquid to gas.

C)

It is absorbing heat while changing from liquid to gas.

D)

Spontaneous gasification creates new gas molecules.

Answer:

C

Explanation:

A)

B)

C)

D)

274)

How does pressure affect the boiling temperature of a liquid?

A)

Decreasing the pressure increases the boiling point.

B)

The pressure cannot change once a liquid begins to boil.

C)

Pressure has no effect on the boiling temperature of a liquid.

D)

Increasing the pressure increases the boiling point.

Answer:

D

Explanation:

A)

B)

C)

D)

275)

What is the AHRI “A” performance testing condition for air–cooled air–conditioning equipment?

A)

100°F outside ambient, 75°F indoor dry bulb, 72°F indoor wet bulb

B)

95°F outside ambient, 80°F indoor dry bulb, 67°F indoor wet bulb

C)

90°F outside ambient, 85°F indoor dry bulb, 70°F indoor wet bulb

D)

95°F outside ambient, 75°F indoor dry bulb, 75°F indoor wet bulb

Answer:

B

Explanation:

A)

B)

C)

D)

70

276)

How does pressure affect boiling point?

A)

Pressure has no effect on the boiling point of a substance.

B)

Lower pressure decreases the boiling point of a substance.

C)

Higher pressure decreases the boiling point of a substance.

D)

Lower pressure increases the boiling point of a substance.

Answer:

B

Explanation:

A)

B)

C)

D)

277)

The amount of space occupied by matter defines:

A)

The properties of matter.

B)

Mass.

C)

Volume.

D)

Weight.

Answer:

C

Explanation:

A)

B)

C)

D)

278)

How much mechanical work is required to lift a 300–lb compressor 3 ft?

A)

Mechanical force alone will not lift the compressor.

B)

300 lb/3 ft = 100 ft–lb of force

C)

300 lb × 3 ft = 900 ft–lb of force

D)

300 lb of force

Answer:

C

Explanation:

A)

B)

C)

D)

279)

Potential energy is:

A)

Purely theoretical.

B)

Stored energy.

C)

An energy source with promise that has not found practical application.

D)

Energy in motion.

Answer:

B

Explanation:

A)

B)

C)

D)

71

280)

Why is the voltage of electricity increased for transmission over long distances?

A)

It speeds up transmission times.

B)

It increases the resistance of the lines.

C)

It reduces the amount of electricity loss.

D)

It creates an alternating current.

Answer:

C

Explanation:

A)

B)

C)

D)

281)

Why is electricity distributed using extremely high voltages?

A)

To keep current as low as possible and reduce loss through the lines.

B)

Higher voltages are easier to generate than lower voltages, so distributing them as a high

voltage reduces equipment and saves money.

C)

For safety because the insulation on the electrical distribution lines is not as effective at

lower voltages.

D)

High–voltage electricity travels faster than lower–voltage electricity and can get from one

side of the country to the other in seconds.

Answer:

A

Explanation:

A)

B)

C)

D)

282)

The relationship between energy, work, and power can be stated as which of the following?

A)

Power is measured in units of energy, and work is the transfer of power.

B)

Power is required to convert work into energy.

C)

Energy is the ability to do work, work is the result of transferring energy, and power is the

rate at which the work is accomplished.

D)

Work is required to convert energy into power.

Answer:

C

Explanation:

A)

B)

C)

D)

283)

What units are most commonly used to measure large quantities of heat quantity in the United

States?

A)

Therms

B)

Degrees Fahrenheit

C)

Kilocalories

D)

Joules

Answer:

A

Explanation:

A)

B)

C)

D)

72

284)

A battery is an example of:

A)

Kinetic energy.

B)

Perpetual energy.

C)

Potential energy.

D)

Cold fusion.

Answer:

C

Explanation:

A)

B)

C)

D)

285)

Calculate the amount of heat required to change 5 lb of 212°F water to steam.

A)

5 lb × 212°F × 1 BTU/lb = 1,060 BTU

B)

5 lb × 970 BTU/lb = 4,850 BTU

C)

No extra heat is required because the water is already at the boiling point.

D)

The amount of heat required cannot be calculated without knowing the starting

temperature of the water.

Answer:

B

Explanation:

A)

B)

C)

D)

286)

Convert 40° Celsius to Fahrenheit.

A)

40 + 32 = 72; 72 × 1.8 = 129.6°F

B)

40/1.8 = 22.2; 22.2 + 32 = 64.2°F

C)

40 + 40 = 80; 80/1.8 = 44.4; 44.4 – 40 = 4.4°F

D)

40 × 1.8 = 72; 72 + 32 = 104°F

Answer:

D

Explanation:

A)

B)

C)

D)

287)

Convert 100° Kelvin to Celsius.

A)

100 + 273 = 373°C

B)

100 – 460 = – 360°C

C)

100 + 460 = 560°C

D)

100 – 273 = – 173°C

Answer:

D

Explanation:

A)

B)

C)

D)

73

288)

Which of the following statements is TRUE of specific heat capacity?

A)

All substances in a given state have the same specific heat capacity.

B)

Specific heat cannot be calculated for every substance.

C)

Specific heat capacity is only relevant to substances in the solid state.

D)

Each substance has its own specific heat capacity regardless of state.

Answer:

D

Explanation:

A)

B)

C)

D)

289)

Which is the largest similarity between the Kelvin and the Rankine temperature scales?

A)

Both easily convert to Celsius.

B)

Both use the same boiling point.

C)

Both begin at absolute zero.

D)

Both use the same temperature spacing interval.

Answer:

C

Explanation:

A)

B)

C)

D)

290)

The Kelvin temperature scale is:

A)

The absolute temperature scale for Fahrenheit.

B)

The absolute temperature scale for Rankine.

C)

The most common temperature scale used in medicine.

D)

The absolute temperature scale for Celsius.

Answer:

D

Explanation:

A)

B)

C)

D)

291)

What temperature scale uses 0° as the freezing point of water and 100° as the boiling point of

water?

A)

Rankine

B)

Fahrenheit

C)

Kelvin

D)

Celsius

Answer:

D

Explanation:

A)

B)

C)

D)

74

292)

What process occurs when dry ice disappears?

A)

Evaporation

B)

Vaporization

C)

Sublimation

D)

Melting

Answer:

C

Explanation:

A)

B)

C)

D)

293)

The amount of heat required to change 1 pound of a substance 1°F is called:

A)

Latent heat.

B)

Sensible heat.

C)

Specific heat capacity.

D)

Total heat.

Answer:

C

Explanation:

A)

B)

C)

D)

294)

What process causes dew to form on grass?

A)

Condensation

B)

Deposition

C)

Vaporization

D)

Freezing

Answer:

A

Explanation:

A)

B)

C)

D)

295)

What is the purpose of adding fins on the tubing used for heat transfer?

A)

Fins keep small animals out of the unit by closing the gaps between the coils.

B)

Fins protect the coils from dirt.

C)

Fins straighten the air flowing over the coils so that it flows more easily.

D)

Fins increase heat transfer by increasing the surface area.

Answer:

D

Explanation:

A)

B)

C)

D)

75

296)

If water in a cup is 10°C and the cup is 20°C, which way will the heat travel according to the

second law of thermodynamics?

A)

Heat will travel in each of the two directions.

B)

Heat will travel from the cup to the water.

C)

Heat will not travel from one object to another.

D)

Heat will travel from the water to the cup.

Answer:

B

Explanation:

A)

B)

C)

D)

297)

Convert 200° Kelvin to Rankine.

A)

200 + 273 = 473°R

B)

200 × 1.8 = 360°R

C)

200 + 460 = 660°R

D)

200/1.8 = 111.11°R

Answer:

B

Explanation:

A)

B)

C)

D)

298)

According to Pascal’s law, what happens to the pressure of a propane tank as it empties?

A)

The pressure increases toward the top of the tank.

B)

The pressure remains uniform throughout the tank.

C)

The pressure increases toward the bottom of the tank.

D)

Pascal’s law does not explain what happens to pressure.

Answer:

B

Explanation:

A)

B)

C)

D)

299)

The total pressure in a mixture of gases is equal to:

A)

The highest pressure among the gases in the mix.

B)

The sum of all the individual gas partial pressures.

C)

The average of all the individual gas partial pressures.

D)

The lowest pressure among all the gases in the mix.

Answer:

B

Explanation:

A)

B)

C)

D)

76

300)

How will decreasing the size of a container holding gas, increasing the amount of gas in a

container, or increasing the temperature of the gas in a container affect the gas in the container?

A)

Each will increase the pressure of the gas.

B)

Each will increase the volume of the gas.

C)

Each will decrease the volume of the gas.

D)

Each will decrease the pressure of the gas.

Answer:

A

Explanation:

A)

B)

C)

D)

301)

How does atmospheric pressure and a vacuum relate to manometers?

A)

A manometer may use a vacuum and atmospheric pressure to operate.

B)

The manometer equalizes pressure of a vacuum.

C)

The manometer can detect a vacuum at absolute pressure.

D)

A manometer checks pressure greater than atmospheric pressure.

Answer:

A

Explanation:

A)

B)

C)

D)

302)

Can changes in atmospheric pressure affect refrigeration gauge pressure readings?

A)

Since refrigeration systems are closed to the atmosphere, atmospheric pressure has no effect

on refrigeration gauge pressure readings.

B)

Atmospheric pressure changes can affect compound gauge readings, but not high–pressure

gauge readings.

C)

Changes in atmospheric pressure can affect the final reading by changing the calibration

point of the gauges.

D)

Atmospheric pressure changes can affect high–pressure gauge readings, but not compound

gauge readings.

Answer:

C

Explanation:

A)

B)

C)

D)

77

303)

What would a barometric pressure reading of 28 in Hg be in psia?

A)

28 in Hg + 15 = 43 psia (rounded)

B)

28 in Hg/2 = 14 psia (rounded)

C)

A 28 in Hg barometric reading is equivalent to 28 psia.

D)

28 in Hg – 15 = 13 psia (rounded)

Answer:

B

Explanation:

A)

B)

C)

D)

304)

Pressure is defined as:

A)

Force per unit area.

B)

Applied force.

C)

The average applied force.

D)

The product of density and specific volume.

Answer:

A

Explanation:

A)

B)

C)

D)

305)

What is the pressure at the bottom of a water tank that has a cross section of 10 ft2 and is filled

with water to a depth of 40 ft?

305)

A)

(40 ft × 0.433 lb/ft)/10 ft2 = 1.7 psi (rounded)

B)

(40 ft × 10 ft2)/0.433 = 924 psi (rounded)

C)

40 ft × 0.433 lb/ft × 10 ft2 = 170 psi (rounded)

D)

40 ft × 0.433 lb/ft = 17 psi (rounded)

Answer:

D

Explanation:

A)

B)

C)

D)

78

306)

Convert a reading of 18 in Hg vacuum to psia.

A)

18 in Hg + 30 = 48 psia (rounded)

B)

18 in Hg/2 = 9 psia (rounded)

C)

30 — 18 in Hg vacuum = 12 in Hg absolute (rounded)

12 in Hg absolute/2 = 6 psia (rounded)

D)

30 + 18 in Hg vacuum = 48 in Hg absolute (rounded)

48 in Hg absolute/2 = 24 psia (rounded)

Answer:

C

Explanation:

A)

B)

C)

D)

307)

A manometer is attached to a vacuum pump, which results in unequal pressure between each of

the two arms. How is the vacuum measured?

A)

The side that is attached to the vacuum is gauged.

B)

The movement of fluid in each side is compared.

C)

A gauge attaches to the bottom of the manometer.

D)

The side that is open to the atmosphere is gauged.

Answer:

B

Explanation:

A)

B)

C)

D)

308)

What would be the final volume of 4 ft3 of gas that is compressed from 60°F at 70 psig to 150° at

210 psig?

308)

A)

22 ft3

B)

2.2 ft3

C)

4.4 ft3

D)

1.8 ft3

Answer:

D

Explanation:

A)

B)

C)

D)

309)

The bar system of pressure measurement is used primarily:

A)

By countries on the SI system.

B)

In countries with a high per capita consumption of alcoholic beverages.

C)

In third–world countries where regular pressure gauges are too costly.

D)

In the United States.

Answer:

A

Explanation:

A)

B)

C)

D)

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310)

What is the relationship between atoms and molecules?

A)

Atoms are made up of molecules.

B)

They are both weightless.

C)

They are two words for the same thing.

D)

Molecules are made up of atoms.

Answer:

D

Explanation:

A)

B)

C)

D)

311)

How do industry organizations make it easier to compare testing results and rating for HVACR

equipment?

A)

Industry organizations simply follow guidelines that are determined by the U.S.

government.

B)

Industry organizations determine a set of standard conditions that make all HVACR testing

results comparable.

C)

Industry organizations use a set of guidelines that are determined by the individual states.

D)

Industry organizations state that there are too many standards in place to make testing

results comparable.

Answer:

B

Explanation:

A)

B)

C)

D)

312)

The indoor dry bulb temperature for AHRI rating condition “A” is:

A)

75°F.

B)

67°F.

C)

80°F.

D)

65°F.

Answer:

C

Explanation:

A)

B)

C)

D)

313)

The point at which water or another substance may exist simultaneously as a solid, liquid, and gas

is:

A)

Triple equilibrium.

B)

Triple point.

C)

Thermal equilibrium.

D)

Critical point.

Answer:

B

Explanation:

A)

B)

C)

D)

80