Engineering Materials and Metrology MCQ With Answers for JKSSB Junior Engineer (Mechanical)

Technical · 2026-10-21 · 6 min read

Engineering materials, metrology and industrial engineering questions are short and factual: alloys, heat treatment, measuring instruments, fits and tolerances, and project and inventory methods. This page gives a revision list and then solved MCQs with explanations.

Quick revision list

  • Alloys: brass is copper and zinc, bronze is copper and tin, and stainless steel has at least about 10.5% chromium
  • Heat treatment: annealing, normalising, quenching, tempering and case hardening
  • Structures: pearlite at 0.8% carbon, austenite as a solid solution in gamma iron
  • Metrology: vernier least count 0.02 mm, micrometer 0.01 mm, slip gauges and go/no-go gauges, and clearance and interference fits
  • Industrial engineering: break-even, EOQ, ABC analysis, PERT and CPM, and the critical path as the longest path

Worked numerical problems

  • Vernier least count: if 1 main scale division is 1 mm and 50 vernier divisions equal 49 mm, the least count is 1 − 49/50 = 0.02 mm
  • Micrometer reading: a sleeve reading of 6.5 mm and a thimble reading of 23 divisions at 0.01 mm each give 6.5 + 0.23 = 6.73 mm
  • Tolerance: a shaft specified as 25 mm with limits of 25.00 and 24.98 has a tolerance of 0.02 mm
  • Economic order quantity: with yearly demand of 1,200 units, an ordering cost of ₹50 and a holding cost of ₹6 per unit a year, EOQ = √(2DS ÷ H) = √(2 × 1,200 × 50 ÷ 6) = 141 units
  • Break-even: with fixed costs of ₹60,000, a selling price of ₹50 and a variable cost of ₹30, the break-even output is 60,000 ÷ 20 = 3,000 units

The iron–carbon diagram

The eutectoid point is at 0.8% carbon and 723 °C, where austenite changes to pearlite. The eutectic point is at 4.3% carbon and 1,147 °C. Austenite can dissolve up to 2.14% carbon, while ferrite dissolves at most 0.02%. Steels have less than about 2% carbon and cast irons have more. Low-carbon steel has under 0.3% carbon, medium-carbon steel has 0.3% to 0.6%, and high-carbon steel has 0.6% to 1.5%.

Hardness and impact tests

  • Brinell: a hardened steel ball is pressed into the surface
  • Rockwell: a diamond cone or a steel ball gives a direct reading from the depth of the dent
  • Vickers: a diamond pyramid is used and the diagonal of the dent is measured
  • Charpy and Izod: a swinging hammer breaks a notched specimen and measures the energy absorbed, which shows toughness

Heat treatment summary

Annealing softens steel by heating and cooling slowly in the furnace. Normalising heats the steel above the critical range and cools it in still air. Hardening heats the steel and quenches it in water or oil. Tempering reheats a hardened steel to a lower temperature to reduce brittleness. Case hardening gives a hard surface and a tough core, using carburising, nitriding or cyaniding.

Limits, fits and tolerances

A hole-basis system keeps the hole's lower limit fixed and varies the shaft. A clearance fit leaves a gap, a transition fit may leave a gap or an interference, and an interference fit needs force or heat to assemble. Go and no-go gauges check whether a part is within its limits quickly. Slip gauges are length standards and are built up by wringing.

Industrial engineering ideas

Work study combines method study and work measurement. ABC analysis ranks inventory by value, with A items being a small number of high-value items. In a project network, the critical path is the longest path, and float is the spare time on other paths. Total quality management aims at continuous improvement involving every person in the organisation.

Questions candidates ask

Why is steel hardened and then tempered? Hardening makes the steel hard but brittle, and tempering reduces the brittleness while keeping most of the hardness.

What is the difference between accuracy and precision? Accuracy is closeness to the true value, and precision is the closeness of repeated readings to each other.

What is a thermosetting plastic? One that sets permanently on heating, such as Bakelite, and cannot be softened again.

Practise

Solve the MCQs below, then read the exam guide. Back to the JE Mechanical guide.

By Shivam · Written with AI assistance and fact-checked · Questions on this page are original · Editorial policy · Report an error

Practice questions

Q1. The least count of a standard vernier calliper is usually:

  1. 0.2 mm
  2. 0.5 mm
  3. 1 mm
  4. 0.02 mm
Show answer

0.02 mm — Many verniers have a least count of 0.02 mm, or 0.1 mm on simple ones.

Q2. The least count of a standard micrometer screw gauge is:

  1. 1 mm
  2. 0.001 mm
  3. 0.01 mm
  4. 0.1 mm
Show answer

0.01 mm — The pitch is 0.5 mm with 50 divisions on the thimble.

Q3. Slip gauges are used as:

  1. Cutting tools
  2. Length standards for calibration
  3. Bearings
  4. Clamps
Show answer

Length standards for calibration — They are wrung together to build up exact lengths.

Q4. A go/no-go gauge is used to:

  1. Mark the work
  2. Measure the exact size
  3. Check whether a dimension is within its tolerance
  4. Cut threads
Show answer

Check whether a dimension is within its tolerance — The go end must enter and the no-go end must not.

Q5. A limit of size gives the:

  1. Average size
  2. Material of the part
  3. Surface finish
  4. Maximum and minimum permissible dimensions
Show answer

Maximum and minimum permissible dimensions — The difference between them is the tolerance.

Q6. In the system of fits, a clearance fit means the shaft is:

  1. Always larger than the hole
  2. Pressed into the hole
  3. Always smaller than the hole
  4. Equal to the hole
Show answer

Always smaller than the hole — A running fit is an example.

Q7. Interference fit is used when:

  1. A permanent assembly with no relative motion is needed
  2. Parts must slide freely
  3. Parts must be easily disassembled
  4. Lubrication is needed
Show answer

A permanent assembly with no relative motion is needed — The shaft is larger than the hole before assembly.

Q8. A dial gauge is mainly used for:

  1. Measuring large lengths
  2. Cutting threads
  3. Marking out
  4. Comparing and checking small variations, such as runout
Show answer

Comparing and checking small variations, such as runout — It amplifies small movements of the plunger.

Q9. Surface roughness is commonly expressed by:

  1. Ra, the arithmetic average roughness
  2. Rt, the temperature
  3. Rp, the pitch
  4. Rm, the mean diameter
Show answer

Ra, the arithmetic average roughness — It is measured in micrometres.

Q10. Accuracy refers to:

  1. The least count
  2. How close a measurement is to the true value
  3. How close repeated measurements are to each other
  4. The size of the instrument
Show answer

How close a measurement is to the true value — Precision refers to repeatability.

Q11. Steel is an alloy of iron and:

  1. Carbon
  2. Copper
  3. Zinc
  4. Aluminium
Show answer

Carbon — Plain carbon steel has up to about 2% carbon.

Q12. Cast iron has a carbon content of about:

  1. 0.8%
  2. 2% to 4%
  3. Below 0.02%
  4. 0.1% to 0.3%
Show answer

2% to 4% — Higher carbon makes it hard and brittle.

Q13. Mild steel contains carbon of about:

  1. 0.1% to 0.25%
  2. 0.8% to 1.5%
  3. 5%
  4. 2% to 4%
Show answer

0.1% to 0.25% — It is the most widely used structural steel.

Q14. Brass is an alloy of:

  1. Copper and nickel
  2. Copper and zinc
  3. Copper and tin
  4. Iron and zinc
Show answer

Copper and zinc — Bronze is copper and tin.

Q15. Bronze is an alloy of:

  1. Copper and zinc
  2. Lead and tin
  3. Aluminium and copper
  4. Copper and tin
Show answer

Copper and tin — It is used for bearings and gears.

Q16. Stainless steel contains chromium of at least about:

  1. 30%
  2. 10.5%
  3. 50%
  4. 1%
Show answer

10.5% — Chromium forms a protective oxide layer.

Q17. Which is the process of heating steel and cooling it slowly in a furnace to soften it?

  1. Case hardening
  2. Quenching
  3. Annealing
  4. Tempering
Show answer

Annealing — It relieves internal stresses and improves machinability.

Q18. Quenching of heated steel in water or oil makes it:

  1. Magnetic
  2. Lighter
  3. Soft and ductile
  4. Hard and brittle
Show answer

Hard and brittle — Rapid cooling forms martensite.

Q19. Tempering is done after hardening to:

  1. Add carbon
  2. Melt the steel
  3. Reduce brittleness and relieve stress
  4. Increase hardness
Show answer

Reduce brittleness and relieve stress — It reheats steel to a moderate temperature.

Q20. Case hardening produces a hard outer layer and:

  1. A hard core
  2. A soft, tough core
  3. No change in core
  4. A brittle core
Show answer

A soft, tough core — Carburising adds carbon to the surface.

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