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EEI MASS Practice Questions (2026) — Free Sample Questions with Answers

15 free EEI MASS questions from our 150-question bank, grouped by content domain. Each answer explains why the right option is right — and why every wrong option is wrong.

Reading Comprehension (4)Mechanical Concepts (6)Assembling Objects (3)Mathematical Usage (2)
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Reading Comprehension

Question 1

Range, Approach, and the Weather: Reading a Cooling Tower

1The condenser at a steam plant needs a steady supply of cool water, and in many plants that water comes from a cooling tower. Warm water from the condenser is pumped to the top of the tower and allowed to fall through it while air moves past. A small part of the water evaporates, and evaporation draws heat out of the water that remains. The cooled water collects in a basin and returns to the condenser to pick up heat again.

2Towers move air in one of two ways. A natural-draft tower is the tall, curved concrete shell often seen from the highway. Warm, moist air inside the shell is lighter than the air outside, so it rises out of the top on its own, the way smoke rises up a chimney, and cooler air is drawn in near the bottom. A mechanical-draft tower is much shorter and uses large fans to push or pull the air. Fans give operators more control, but they use electric power and need regular maintenance.

3Two numbers describe how a tower is working. The range is the difference between the temperature of the hot water entering the tower and the temperature of the cold water leaving it. If water arrives at 105°F and leaves at 85°F, the range is 20 degrees. The range is set mostly by how much heat the condenser puts into the water. The approach is the difference between the cold-water temperature and the wet-bulb temperature of the outside air.

4The wet-bulb temperature is read from a thermometer whose bulb is wrapped in a wet cloth and kept in moving air. It is lower than the ordinary air temperature whenever the air is not saturated, that is, whenever the air could still hold more water vapor, because water evaporating from the cloth cools the bulb. The wet-bulb reading shows how much cooling by evaporation the air can still provide. A tower can bring its water close to the wet-bulb temperature, but never below it.

5These ideas explain why tower performance changes with the weather. On a dry day the wet-bulb temperature is low, and the tower can deliver cold water even when the air feels hot. On a humid day the wet-bulb temperature rises close to the air temperature, and the water leaving the tower is warmer. If the approach grows larger while the weather and load stay the same, operators look for a problem in the tower itself, such as clogged fill, a failed fan, or poor water spray.

What is the main purpose of paragraph 2?

Show answer & explanation

Answer: B

To explain why evaporation cools the water: Evaporation is explained in paragraph 1.

To compare the two ways that towers move air: Correct. Paragraph 2 opens "Towers move air in one of two ways" and then describes natural-draft and mechanical-draft towers.

To show that tall towers cool water best: Not stated: paragraph 2 never says which kind of tower cools better.

To describe how tower fans are maintained: True-but-partial: maintenance is mentioned in one phrase, not explained.

A topic sentence such as "Towers move air in one of two ways" usually announces the paragraph's purpose.

Question 2

Range, Approach, and the Weather: Reading a Cooling Tower

1The condenser at a steam plant needs a steady supply of cool water, and in many plants that water comes from a cooling tower. Warm water from the condenser is pumped to the top of the tower and allowed to fall through it while air moves past. A small part of the water evaporates, and evaporation draws heat out of the water that remains. The cooled water collects in a basin and returns to the condenser to pick up heat again.

2Towers move air in one of two ways. A natural-draft tower is the tall, curved concrete shell often seen from the highway. Warm, moist air inside the shell is lighter than the air outside, so it rises out of the top on its own, the way smoke rises up a chimney, and cooler air is drawn in near the bottom. A mechanical-draft tower is much shorter and uses large fans to push or pull the air. Fans give operators more control, but they use electric power and need regular maintenance.

3Two numbers describe how a tower is working. The range is the difference between the temperature of the hot water entering the tower and the temperature of the cold water leaving it. If water arrives at 105°F and leaves at 85°F, the range is 20 degrees. The range is set mostly by how much heat the condenser puts into the water. The approach is the difference between the cold-water temperature and the wet-bulb temperature of the outside air.

4The wet-bulb temperature is read from a thermometer whose bulb is wrapped in a wet cloth and kept in moving air. It is lower than the ordinary air temperature whenever the air is not saturated, that is, whenever the air could still hold more water vapor, because water evaporating from the cloth cools the bulb. The wet-bulb reading shows how much cooling by evaporation the air can still provide. A tower can bring its water close to the wet-bulb temperature, but never below it.

5These ideas explain why tower performance changes with the weather. On a dry day the wet-bulb temperature is low, and the tower can deliver cold water even when the air feels hot. On a humid day the wet-bulb temperature rises close to the air temperature, and the water leaving the tower is warmer. If the approach grows larger while the weather and load stay the same, operators look for a problem in the tower itself, such as clogged fill, a failed fan, or poor water spray.

Water leaves a tower at 80°F while the wet-bulb temperature is 74°F. Which conclusion follows from the passage?

Show answer & explanation

Answer: C

The range is 6 degrees, because range compares cold water with the wet bulb.: Confuses range with approach; range compares hot and cold water (paragraph 3).

Running more fans could cool the water to 70°F on this day.: Contradicts paragraph 4: no tower can cool water below the 74°F wet-bulb temperature.

The approach is 6 degrees, and the water cannot be cooled below 74°F.: Correct. Approach is cold water minus wet bulb (80 − 74 = 6), and paragraph 4 says a tower brings water close to the wet-bulb temperature "but never below it."

The outside air must be fully saturated with water vapor today.: Unsupported: saturated air would make the air and wet-bulb temperatures equal, and the air temperature is not given.

Apply the passage's definitions to new numbers: approach = cold water minus wet bulb, and the wet bulb is the floor no tower can pass.

Question 3

Range, Approach, and the Weather: Reading a Cooling Tower

1The condenser at a steam plant needs a steady supply of cool water, and in many plants that water comes from a cooling tower. Warm water from the condenser is pumped to the top of the tower and allowed to fall through it while air moves past. A small part of the water evaporates, and evaporation draws heat out of the water that remains. The cooled water collects in a basin and returns to the condenser to pick up heat again.

2Towers move air in one of two ways. A natural-draft tower is the tall, curved concrete shell often seen from the highway. Warm, moist air inside the shell is lighter than the air outside, so it rises out of the top on its own, the way smoke rises up a chimney, and cooler air is drawn in near the bottom. A mechanical-draft tower is much shorter and uses large fans to push or pull the air. Fans give operators more control, but they use electric power and need regular maintenance.

3Two numbers describe how a tower is working. The range is the difference between the temperature of the hot water entering the tower and the temperature of the cold water leaving it. If water arrives at 105°F and leaves at 85°F, the range is 20 degrees. The range is set mostly by how much heat the condenser puts into the water. The approach is the difference between the cold-water temperature and the wet-bulb temperature of the outside air.

4The wet-bulb temperature is read from a thermometer whose bulb is wrapped in a wet cloth and kept in moving air. It is lower than the ordinary air temperature whenever the air is not saturated, that is, whenever the air could still hold more water vapor, because water evaporating from the cloth cools the bulb. The wet-bulb reading shows how much cooling by evaporation the air can still provide. A tower can bring its water close to the wet-bulb temperature, but never below it.

5These ideas explain why tower performance changes with the weather. On a dry day the wet-bulb temperature is low, and the tower can deliver cold water even when the air feels hot. On a humid day the wet-bulb temperature rises close to the air temperature, and the water leaving the tower is warmer. If the approach grows larger while the weather and load stay the same, operators look for a problem in the tower itself, such as clogged fill, a failed fan, or poor water spray.

As used in paragraph 4, the word "saturated" means that the air

Show answer & explanation

Answer: A

holds all the water vapor it can: Correct. Paragraph 4 explains the word itself: air that is not saturated "could still hold more water vapor."

is moving quickly through the fill: Moving air is needed for the wet-bulb reading, but it is not what "saturated" means.

is warmer than the water below it: The passage never ties saturation to the air being warmer than the water.

has passed over a wet cloth: The wet cloth covers the thermometer bulb; it does not define saturated air.

Training manuals often define a term right after it, set off by "that is"; look for that restatement.

Question 4

According to the passage, what is the range of a cooling tower?

Range, Approach, and the Weather: Reading a Cooling Tower

1The condenser at a steam plant needs a steady supply of cool water, and in many plants that water comes from a cooling tower. Warm water from the condenser is pumped to the top of the tower and allowed to fall through it while air moves past. A small part of the water evaporates, and evaporation draws heat out of the water that remains. The cooled water collects in a basin and returns to the condenser to pick up heat again.

2Towers move air in one of two ways. A natural-draft tower is the tall, curved concrete shell often seen from the highway. Warm, moist air inside the shell is lighter than the air outside, so it rises out of the top on its own, the way smoke rises up a chimney, and cooler air is drawn in near the bottom. A mechanical-draft tower is much shorter and uses large fans to push or pull the air. Fans give operators more control, but they use electric power and need regular maintenance.

3Two numbers describe how a tower is working. The range is the difference between the temperature of the hot water entering the tower and the temperature of the cold water leaving it. If water arrives at 105°F and leaves at 85°F, the range is 20 degrees. The range is set mostly by how much heat the condenser puts into the water. The approach is the difference between the cold-water temperature and the wet-bulb temperature of the outside air.

4The wet-bulb temperature is read from a thermometer whose bulb is wrapped in a wet cloth and kept in moving air. It is lower than the ordinary air temperature whenever the air is not saturated, that is, whenever the air could still hold more water vapor, because water evaporating from the cloth cools the bulb. The wet-bulb reading shows how much cooling by evaporation the air can still provide. A tower can bring its water close to the wet-bulb temperature, but never below it.

5These ideas explain why tower performance changes with the weather. On a dry day the wet-bulb temperature is low, and the tower can deliver cold water even when the air feels hot. On a humid day the wet-bulb temperature rises close to the air temperature, and the water leaving the tower is warmer. If the approach grows larger while the weather and load stay the same, operators look for a problem in the tower itself, such as clogged fill, a failed fan, or poor water spray.

Show answer & explanation

Answer: B

The air temperature minus the wet-bulb temperature: Not a term the passage defines; paragraph 4 only says the wet-bulb reading is lower than the air temperature.

The hot-water temperature minus the cold-water temperature: Correct. Paragraph 3 defines range as "the difference between the temperature of the hot water entering" and the cold water leaving.

The highest water temperature the condenser can accept: Plausible-sounding, but the passage never gives a condenser limit.

The cold-water temperature minus the outside wet-bulb temperature: That is the approach, defined in the last sentence of paragraph 3.

When a passage defines two similar terms, note exactly which two temperatures each one compares.

Mechanical Concepts

Question 5

Both ports of the cylinder are connected to the same air line at the same pressure. Ignoring friction, which way will the rod move? (If neither, mark C.)

Air supplyABRod
Show answer & explanation

Answer: B

Direction A: This would need a larger force on the rod side, but the rod side has the smaller area.

Direction B: Correct. Force = pressure × area. The cap-end face (left) has the full piston area, while the rod-end face loses the area covered by the rod. With equal pressure, the left side pushes harder, so the rod moves out, toward B.

Neither: Equal pressures balance only on equal areas; the rod makes the right-hand face smaller.

Equal pressure on both sides of a piston does not balance it when one side has a rod: the full-area cap side wins and the rod extends.

Question 6

The flat board has a heavy weight bolted to one corner. It is hung from a nail through the hole shown. Which drawing shows how it will hang at rest?

The boardheavy weightholeABC
Show answer & explanation

Answer: C

Position A: Ignored the weight: a board with extra weight at one corner cannot hang level, because its centre of gravity is off to that side.

Position B: Swung the wrong way: this lifts the heavy corner up, putting the centre of gravity off to the side of the nail.

Position C: Correct. A hanging object swings until its centre of gravity is directly below the support. The weight pulls the centre of gravity toward the weighted corner, so that corner swings down, as in C.

Anything hung from one point comes to rest with its centre of gravity straight below that point.

Question 7

The tank is full, with water standing in its open neck. Points A and B are at the same height. Where is the pressure greater? (If equal, mark C.)

ABopen neck
Show answer & explanation

Answer: C

Point A: Looked only at the tall column of water straight above A; the pressure is spread through the connected water and depends on depth below the surface.

Point B: The roof of the tank above B does not add pressure of its own; B is no deeper than A.

Equal: Correct. In still water the pressure depends only on depth below the free surface. A and B are the same depth below the water surface in the neck, so their pressures are equal, even though only A has water straight overhead.

All points at the same depth in one connected body of still liquid have the same pressure, whatever lies directly above them.

Question 8

The pinion turns counterclockwise between rack A above it and rack B below it. Which rack moves to the right? (If both, mark C.)

Rack ARack B
Both racks can slide only left or right.
Show answer & explanation

Answer: B

Rack A: The top of a counterclockwise pinion moves to the left, so rack A moves left.

Rack B: Correct. A rack moves with the pinion teeth it touches. On a counterclockwise pinion the bottom teeth move to the right, so rack B, meshed at the bottom, moves right.

Both A and B: The racks touch opposite sides of the pinion, which move in opposite directions, so the racks cannot move the same way.

Racks on opposite sides of one pinion always move in opposite directions.

Question 9

Each frictionless tackle holds a 180 lb load with one upper and one lower pulley. Which pull rope needs less force to hold the load? (If equal, mark C.)

ABPull180 lbPull180 lb
Each tackle has one upper and one lower pulley. The pulleys are frictionless.
Show answer & explanation

Answer: A

  1. 1. A: end tied to the lower block, 3 supporting segments: 180 ÷ 3 = 60 lb
  2. 2. B: end tied to the upper block, 2 supporting segments: 180 ÷ 2 = 90 lb

Tackle A: Correct. Count the rope segments holding up the lower block. In A the rope’s end is tied to the lower block, so three segments support it: 180 ÷ 3 = 60 lb. In B only two do: 180 ÷ 2 = 90 lb.

Tackle B: Pulling down in B is easier on the body, but B has only two supporting segments, so it needs 90 lb.

Tackles A and B equally: The same pulleys do not guarantee the same advantage; where the rope’s end is tied changes the count from 2 to 3.

Tying the rope’s end to the moving block adds a supporting segment, so the same two pulleys give an advantage of 3 instead of 2.

Question 10

A spreader beam carries 200 lb at its left end and 100 lb at its right end. At which eye should the hook attach to lift it level?

ABC3 ft1.5 ft1.5 ft3 ft200 lb100 lb
Each load hangs at an end of the beam. Ignore the weight of the beam.
Show answer & explanation

Answer: A

  1. 1. Eye A: 200 lb × 3 ft = 600 lb-ft on the left
  2. 2. 100 lb × 6 ft = 600 lb-ft on the right
  3. 3. The moments match, so the beam hangs level

Eye A: Correct. Moment balance about the hook: at eye A the 200 lb load is 3 ft away and the 100 lb load is 6 ft away, and 200 × 3 = 100 × 6, so the beam hangs level.

Eye B: The center eye ignores the uneven loads; the heavier left end would drop.

Eye C: Eye C is toward the lighter load, so the heavy left end would tip down even farther.

Hook directly above the combined center of gravity, which lies toward the heavier load: twice the weight, half the distance.

Assembling Objects

Question 11

Which figure shows how the pieces fit together?

ABCD
Pieces at left; possible assemblies A–D at right.
Show answer & explanation

Answer: A

Assembly A: Correct. The L-shaped piece, the two T-shaped pieces and the straight strip of four squares fill the square exactly; the L is turned, not flipped.

Assembly B: The L-shaped piece is a mirror image of the one given: its foot points the opposite way.

Assembly C: The straight strip is cut in two, giving five pieces instead of four.

Assembly D: One square has moved from a T-shaped piece to the strip, so neither piece matches.

For an L-shaped piece, turn it in your mind until the long side lines up; if the foot then points the other way, it is a mirror image.

Question 12

Which figure shows how the pieces fit together?

ABCD
Pieces at left; possible assemblies A–D at right.
Show answer & explanation

Answer: D

Assembly A: The diamond has been cut into two triangles, giving four pieces instead of three.

Assembly B: One half is cut straight down the middle into two four-sided pieces; there is no triangle or diamond.

Assembly C: One half is cut corner to corner into two different triangles; there is no diamond.

Assembly D: Correct. The half-hexagon, the triangle and the diamond fill the outline with no gaps, and each matches its part exactly.

Name each given piece (half-hexagon, triangle, diamond) and look for a panel that contains exactly that set.

Question 13

Which figure shows the parts correctly assembled?

ABABABCD
Parts at left; possible assemblies A–D at right.
Show answer & explanation

Answer: C

Assembly A: The triangle is joined at a sharp corner, but B is its right-angle corner.

Assembly B: The bar ends at the centre of the circle, but A is on the circle's edge.

Assembly C: Correct. One end of the bar meets the circle's edge (A) and the other end meets the triangle's right-angle corner (B), with every part its original size.

Assembly D: The triangle is a mirror image of the one in the parts box: its long and short sides are swapped around the right angle.

Check each lettered joint in turn: the right part, the right spot on that part, and the same size as in the parts box.

Mathematical Usage

Question 14
Use these facts for the questions that follow
Fact
1 foot = 12 inches
1 yard = 3 feet
1 mile = 5,280 feet
1 mile = 1,760 yards
1 fathom = 6 feet

42 inches = ? feet

Show answer & explanation

Answer: A

  1. 1. 1 foot = 12 inches, so divide inches by 12
  2. 2. 42 ÷ 12 = 3.5 feet

3.5: Correct. 1 foot = 12 inches, so divide by 12: 42 ÷ 12 = 3.5 feet.

4.2: Moved the decimal point (divided by 10) instead of dividing by 12.

14: Divided by 3, the feet-per-yard fact, instead of by 12.

504: Multiplied by 12 instead of dividing.

N (not given): Not the answer: 3.5 appears among the choices.

Going from a smaller unit (inches) to a larger unit (feet), divide by the conversion factor.

Question 15

9 feet = ? inches

Use these facts for the questions that follow
Fact
1 foot = 12 inches
1 yard = 3 feet
1 mile = 5,280 feet
1 mile = 1,760 yards
1 fathom = 6 feet
Show answer & explanation

Answer: D

  1. 1. 1 foot = 12 inches, so multiply feet by 12
  2. 2. 9 × 12 = 108 inches

.75: Divided by 12 instead of multiplying.

3: Used 1 yard = 3 feet and divided, which gives yards, not inches.

27: Multiplied by 3, the feet-per-yard fact, instead of by 12.

108: Correct. 1 foot = 12 inches, so multiply by 12: 9 × 12 = 108 inches.

N (not given): Not the answer: 108 appears among the choices.

Going from a larger unit (feet) to a smaller unit (inches), multiply by the conversion factor.

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