AR GP Gypsum & Plaster Contractor
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the main ingredient in gypsum plaster?
A. Lime
B. Cement
C. Gypsum
D. Sand
Answer: Gypsum
Rationale: Gypsum plaster is made primarily from the mineral gypsum
(CaSO₄·2H₂O), which provides its setting and hardening properties.
2. Which of the following is a common use of gypsum board?
A. Roofing
B. Flooring
C. Interior walls and ceilings
D. Exterior foundation
Answer: Interior walls and ceilings
Rationale: Gypsum board is widely used for interior wall and ceiling
applications due to its fire resistance and smooth finish.
3. The setting time of gypsum plaster can be controlled by:
A. Temperature only
B. Additives and retarders
C. Sand content
D. Humidity only
,Answer: Additives and retarders
Rationale: Setting time of gypsum can be modified using chemical additives
like retarders to slow down or accelerators to speed up the process.
4. Which type of gypsum plaster is suitable for high humidity areas?
A. Lime plaster
B. Cement plaster
C. Water-resistant gypsum plaster
D. Standard gypsum plaster
Answer: Water-resistant gypsum plaster
Rationale: Water-resistant gypsum plaster contains additives that reduce
water absorption, making it suitable for bathrooms or kitchens.
5. What is the ideal thickness of a single coat gypsum plaster on a wall?
A. 5–10 mm
B. 10–15 mm
C. 20–25 mm
D. 30–35 mm
Answer: 10–15 mm
Rationale: A thickness of 10–15 mm ensures proper adhesion and reduces
the risk of cracking or sagging.
6. Which tool is primarily used to apply gypsum plaster?
A. Trowel
B. Hawk and trowel
C. Spade
D. Float
Answer: Hawk and trowel
Rationale: A hawk holds the plaster, while a trowel is used to apply and
smooth it on the wall.
7. The primary cause of cracking in gypsum plaster is:
A. Using too much water
B. Rapid drying or shrinkage
, C. Adding sand
D. Poor surface preparation
Answer: Rapid drying or shrinkage
Rationale: Cracks often occur when gypsum plaster dries too quickly,
causing shrinkage stresses.
8. Which of the following is a fire-resistant property of gypsum plaster?
A. Low thermal conductivity
B. Water of crystallization releases steam
C. High density
D. Reflective surface
Answer: Water of crystallization releases steam
Rationale: Gypsum contains water of crystallization which, when exposed
to fire, releases steam and slows heat transfer.
9. What is the recommended substrate preparation for gypsum plaster?
A. Apply directly on smooth surfaces
B. Clean, damp, and slightly roughened surface
C. Apply over wet paint
D. Sanded glossy surface
Answer: Clean, damp, and slightly roughened surface
Rationale: Proper substrate preparation ensures strong adhesion and
prevents plaster from falling off.
10. How long does it take for gypsum plaster to set under normal
conditions?
A. 5–10 minutes
B. 10–15 minutes
C. 30–60 minutes
D. 2–3 hours
Answer: 30–60 minutes
Rationale: Standard gypsum plaster typically sets within 30–60 minutes,
depending on temperature and additives.
Exam Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the main ingredient in gypsum plaster?
A. Lime
B. Cement
C. Gypsum
D. Sand
Answer: Gypsum
Rationale: Gypsum plaster is made primarily from the mineral gypsum
(CaSO₄·2H₂O), which provides its setting and hardening properties.
2. Which of the following is a common use of gypsum board?
A. Roofing
B. Flooring
C. Interior walls and ceilings
D. Exterior foundation
Answer: Interior walls and ceilings
Rationale: Gypsum board is widely used for interior wall and ceiling
applications due to its fire resistance and smooth finish.
3. The setting time of gypsum plaster can be controlled by:
A. Temperature only
B. Additives and retarders
C. Sand content
D. Humidity only
,Answer: Additives and retarders
Rationale: Setting time of gypsum can be modified using chemical additives
like retarders to slow down or accelerators to speed up the process.
4. Which type of gypsum plaster is suitable for high humidity areas?
A. Lime plaster
B. Cement plaster
C. Water-resistant gypsum plaster
D. Standard gypsum plaster
Answer: Water-resistant gypsum plaster
Rationale: Water-resistant gypsum plaster contains additives that reduce
water absorption, making it suitable for bathrooms or kitchens.
5. What is the ideal thickness of a single coat gypsum plaster on a wall?
A. 5–10 mm
B. 10–15 mm
C. 20–25 mm
D. 30–35 mm
Answer: 10–15 mm
Rationale: A thickness of 10–15 mm ensures proper adhesion and reduces
the risk of cracking or sagging.
6. Which tool is primarily used to apply gypsum plaster?
A. Trowel
B. Hawk and trowel
C. Spade
D. Float
Answer: Hawk and trowel
Rationale: A hawk holds the plaster, while a trowel is used to apply and
smooth it on the wall.
7. The primary cause of cracking in gypsum plaster is:
A. Using too much water
B. Rapid drying or shrinkage
, C. Adding sand
D. Poor surface preparation
Answer: Rapid drying or shrinkage
Rationale: Cracks often occur when gypsum plaster dries too quickly,
causing shrinkage stresses.
8. Which of the following is a fire-resistant property of gypsum plaster?
A. Low thermal conductivity
B. Water of crystallization releases steam
C. High density
D. Reflective surface
Answer: Water of crystallization releases steam
Rationale: Gypsum contains water of crystallization which, when exposed
to fire, releases steam and slows heat transfer.
9. What is the recommended substrate preparation for gypsum plaster?
A. Apply directly on smooth surfaces
B. Clean, damp, and slightly roughened surface
C. Apply over wet paint
D. Sanded glossy surface
Answer: Clean, damp, and slightly roughened surface
Rationale: Proper substrate preparation ensures strong adhesion and
prevents plaster from falling off.
10. How long does it take for gypsum plaster to set under normal
conditions?
A. 5–10 minutes
B. 10–15 minutes
C. 30–60 minutes
D. 2–3 hours
Answer: 30–60 minutes
Rationale: Standard gypsum plaster typically sets within 30–60 minutes,
depending on temperature and additives.
