ExxonMobil Test ExxonMobil Mechanical Aptitude 1 — Questions and Answers
Question 1: If Gear A has 20 teeth and Gear B has 40 teeth, and Gear A rotates at 100 RPM, what is the speed of Gear B?
- 25 RPM
- 50 RPM (Correct answer)
- 75 RPM
- 200 RPM
Correct answer: 50 RPM
Gear ratio = 20/40 = 0.5; Gear B speed = 100 × 0.5 = 50 RPM.
Question 2: A valve is used to control fluid flow in a pipeline. Which type of valve provides the best flow control with a quarter-turn operation?
- Gate valve
- Globe valve
- Ball valve (Correct answer)
- Butterfly valve
Correct answer: Ball valve
Ball valves operate with a 90-degree (quarter-turn) rotation and provide reliable on/off flow control.
Question 3: In a hydraulic system, if the input piston has an area of 5 cm² and a force of 100 N is applied, what pressure is generated?
- 10 Pa
- 20 Pa (Correct answer)
- 100 Pa
- 500 Pa
Correct answer: 20 Pa
Pressure = Force ÷ Area = 100 N ÷ 5 cm² = 20 N/cm² (20 Pa in simplified units).
Question 4: Which type of pump is best suited for moving high-viscosity fluids like heavy crude oil?
- Centrifugal pump
- Jet pump
- Gear pump (Correct answer)
- Turbine pump
Correct answer: Gear pump
Gear pumps are positive displacement pumps best suited for high-viscosity fluids because they produce steady flow regardless of viscosity.
Question 5: A lever has its fulcrum 1 meter from a 200 N load. How far from the fulcrum must a 50 N force be applied to balance it?
- 2 meters
- 3 meters
- 4 meters (Correct answer)
- 5 meters
Correct answer: 4 meters
Torque balance: 200 × 1 = 50 × d; d = 200/50 = 4 meters.
Question 6: In a refinery heat exchanger, what is the primary purpose of baffles?
- To prevent corrosion of the tubes
- To increase turbulence and improve heat transfer (Correct answer)
- To reduce the pressure drop across the exchanger
- To filter contaminants from the fluid
Correct answer: To increase turbulence and improve heat transfer
Baffles direct shell-side fluid flow to create turbulence, which significantly improves heat transfer efficiency.
ExxonMobil Test ExxonMobil Mechanical Aptitude 1
If Gear A has 20 teeth and Gear B has 40 teeth, and Gear A rotates at 100 RPM, what is the speed of Gear B?