D52 FACE THE CHALLENGE

Assertion (A): Concrete is strong in compression but weak in tension. Reason (R): Aggregates pull away from each other under compression causing cracks.

• Both A and R are true, and R is the correct explanation of A
• Both A and R are true, but R is not the correct explanation of A
• A is true but R is false
• A is false but R is true

Answer explanation

Concrete's weakness in tension is due to separation of aggregates at the interfacial zone.

Aggregates pull away from each other under tension causing cracks.

Assertion (A): Cast iron pipes are suitable for pressure lines. Reason (R): Cast iron pipes are weak in tensile stress and cannot handle high pressures.

• Both A and R are true, and R is the correct explanation of A
• Both A and R are true, but R is not the correct explanation of A
• A is true but R is false
• A is false but R is true

Answer explanation

Cast iron pipes are strong in compression and are used for pressure lines. Reason is incorrect.

A force of 100 N is applied to an object of mass 25 kg. What is the acceleration?

• 2 m/s²
• 3 m/s²
• 4 m/s²
• 5 m/s²

Answer explanation

Using Newton’s second law: a = F/m = 100/25 = 4 m/s²

What is the pressure exerted by a 500 N force on a surface of area 0.25 m²?

• 2000 Pa
• 2500 Pa
• 1000 Pa
• 1500 Pa

Answer explanation

Pressure = Force / Area = 500 / 0.25= 2000 N/m²

Which type of sleeper is most suitable for high-speed broad gauge tracks?

• Steel
• Cast Iron
• Wooden
• Concrete

Answer explanation

Concrete sleepers are preferred for high-speed broad gauge due to stability and long life.

Which section is also known as ISMC in steel structures?

• I-Section
• C-Channel
• Angle
• T-Section

Answer explanation

ISMC refers to Indian Standard Medium Weight Channels (C-section).

Which sewer material is highly resistant to sulphide corrosion?

• Asbestos cement
• Brick
• Vitrified clay
• RCC

Answer explanation

Vitrified clay resists H₂S corrosion and has a smooth hydraulic surface.

The modulus of elasticity is valid only in which region of stress-strain curve?

• Plastic region
• Proportional limit
• Yield point
• Ultimate point

Answer explanation

Hooke’s law is valid up to proportional limit. Beyond it, material behaves non-linearly.

In plane table surveying, which part is used for centering?

• Plumbing fork with bob
• Spirit level
• Telescopic alidade
• Drawing sheet

Answer explanation

Plumbing fork with bob centers the table exactly over the ground station.

What is the minimum reinforcement in slab using HYSD bars?

• 0.15%
• 0.10%
• 0.12%
• 0.30%

Answer explanation

Minimum reinforcement for HYSD bars in slabs is 0.12% as per code.