Free NATE Core Exam Practice Questions

Sample Practice Questions

Try these 10 sample questions from the NATE Core Exam practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1During service on an R-22 air-conditioning system, which refrigerant release is permitted under the EPA Section 608 venting prohibition?

   1. A. Venting the charge to reduce recovery time
   2. B. Releasing refrigerant to clear a blocked line
   3. C. A de minimis release during a good-faith recovery attempt
   4. D. Bleeding refrigerant to lower an overcharged system

   Answer: C

   Explanation: EPA permits "quantities of refrigerant released while making good faith attempts to recapture and recycle or safely dispose of refrigerant" only within the listed de minimis exception. This covers incidental releases during good-faith recovery, not deliberate venting to clear a line, reduce recovery time, or correct overcharge.

   Reference: Stationary Refrigeration — Prohibition on Venting Refrigerants — Types of Releases, first permitted release

2. 2A tubing dimension is 2.00 inches. What is the equivalent dimension in millimeters?

   1. A. 5.08 mm
   2. B. 25.4 mm
   3. C. 50.8 mm
   4. D. 508 mm

   Answer: C

   Explanation: NIST states that a standard inch "is exactly equivalent to 25.4 mm." Multiplying 2.00 by 25.4 gives 50.8 mm. The other values reflect decimal placement errors or failure to multiply by two.

   Reference: SI Units — Length — When did the metric redefinition of the inch occur?

3. 3A construction print gives an explicit dimension for an equipment opening. Why is using that stated dimension preferred to estimating the opening by measuring the printed image?

   1. A. It makes the drawing independent of its revision status
   2. B. It removes the need to check specified materials
   3. C. It reduces measurement error and permits greater accuracy
   4. D. It changes every drawing view to a full-size representation

   Answer: C

   Explanation: DOE says that specifying actual dimensions is preferred "because it reduces the chances of error and allows greater accuracy and drawing flexibility." This controls how to obtain the opening size; it does not remove revision or material checks or make the print full size.

   Reference: DOE Fundamentals Handbook — Engineering Symbology, Prints, and Drawings, Volume 2 — Module 6, Dimensioning Drawings, p. 5

4. 4A material sample has a mass of 270 grams and a volume of 100 cubic centimeters at the measurement temperature. What is its density?

   1. A. 0.37 g/cm³
   2. B. 2.70 g/cm³
   3. C. 27.0 g/cm³
   4. D. 270 g/cm³

   Answer: B

   Explanation: DOE states, "Density is the measure of the mass per unit volume of a material (density = mass/volume)." Thus 270 ÷ 100 = 2.70 g/cm³. Inverting the ratio or misplacing the decimal gives the incorrect values.

   Reference: DOE Fundamentals Handbook — Chemistry, Volume 1 — Module 1, Chemical Equations, Density, p. 37

5. 5An occupant feels too warm while seated a short distance from a hot unshielded surface, without touching it. Which mechanism transfers heat directly from that surface to the occupant across the gap?

   1. A. Conduction through direct solid contact
   2. B. Convection carried by moving room air
   3. C. Radiant heat exchange across the gap
   4. D. Evaporative heat loss from the skin

   Answer: C

   Explanation: HSE defines thermal radiation as "the heat that radiates from a warm object." The nearby surface can radiate directly to the occupant without contact. Convection carries heat with air, conduction requires a contact path here, and skin evaporation removes heat rather than conveying the surface’s radiation.

   Reference: Thermal Comfort — Six factors indicating thermal comfort — Radiant temperature

6. 6Heat is removed from liquid water so that its temperature falls without a phase change. Which heat category describes this removal?

   1. A. Latent heat of fusion
   2. B. Latent heat of vaporization
   3. C. Latent heat of condensation
   4. D. Sensible heat

   Answer: D

   Explanation: DOE states, "The heat added to or removed from a substance to produce a change in its temperature is called sensible heat." The water remains liquid while its temperature changes. Latent heat instead accompanies a change of phase.

   Reference: DOE Fundamentals Handbook — Thermodynamics, Heat Transfer, and Fluid Flow, Volume 1 — Module 1, Energy, Work, and Heat, p. 20

7. 7What information do polarity dots on a transformer symbol communicate?

   1. A. The turns ratio between the primary and secondary windings
   2. B. The phase relationship between corresponding winding terminals
   3. C. The current ratings assigned to the individual winding terminals
   4. D. The grounding connections between winding terminals and frame

   Answer: B

   Explanation: DOE explains that polarity marks help determine "the phase relationship (polarity) between the input and output terminals of a transformer." Dots indicate relative instantaneous winding polarity. They do not specify turns ratio, current ratings, or grounding connections.

   Reference: DOE Fundamentals Handbook — Engineering Symbology, Prints, and Drawings, Volume 1 — Module 3, Symbology, Transformers, p. 2

8. 8Under OSHA Hazard Communication requirements, when must an employer train an HVAC employee about a newly introduced chemical hazard that the employee has not previously been trained about?

   1. A. When the new hazard is introduced into the work area
   2. B. At the next regularly scheduled annual review
   3. C. After the employee has used the chemical for one month
   4. D. Only after an exposure incident involving that chemical

   Answer: A

   Explanation: OSHA requires training "at the time of their initial assignment, and whenever a new chemical hazard the employees have not previously been trained about is introduced into their work area." The new hazard triggers training; an annual date, elapsed use period, or incident does not replace that trigger.

   Reference: 29 CFR 1910.1200 — Hazard Communication — 1910.1200(h)(1)

9. 9On an undistorted drawing with a scale of 1/4 inch = 1 foot, a measured line is 3 inches long. What actual length does it represent?

   1. A. 0.75 foot
   2. B. 3 feet
   3. C. 6 feet
   4. D. 12 feet

   Answer: D

   Explanation: DOE describes obtaining dimensions by "measuring the drawing and correcting for the scale." Each quarter inch represents one foot, so 3 ÷ 0.25 = 12 feet. Multiplying instead of dividing or treating drawing inches as actual feet produces the distractors.

   Reference: DOE Fundamentals Handbook — Engineering Symbology, Prints, and Drawings, Volume 2 — Module 6, Dimensioning Drawings, p. 5

10. 10Water piping must pass through an exterior wall cavity in a cold climate. In addition to insulating the pipe and air-sealing the cavity, where should the cavity insulation be placed to reduce heat loss from the pipe?

    1. A. Between the pipe and the exterior wall
    2. B. Only between the pipe and the interior finish
    3. C. Only above the pipe near the wall's top plate
    4. D. Only below the pipe near the wall's bottom plate

    Answer: A

    Explanation: The guidance states, "cavity insulation should be installed behind the pipes, between the pipes and the exterior wall." This places thermal resistance between the pipe and cold exterior. Insulation only toward the room, above the pipe, or below it does not provide that exterior-side separation.

    Reference: Insulating Plumbing Pipes — Description, exterior-wall pipe placement