Small fissures or hollows in a stone which renders it liable to decomposition are called
- Ashakes
- Bmottle
- Cshelly bars
- DventsCorrect
Solution
Concept
Vents are small fissures or hollows in a stone that let water and air enter and start decay.
Step-by-step solution
1. List the common defects of stones: vents, mottle, shelly bars, clay holes, sand holes. 2. Small fissures or hollows in a stone are called vents. 3. Water enters through vents, so the stone decays faster. 4. So the answer is (D) vents.
Explanation
Vents are small cracks or hollows in a stone. Water and gases enter through them, and the stone slowly decomposes. So vents make a stone weak and less durable.
Why the other options are wrong
A: Shakes are mainly cracks in timber, not the standard name for small hollows in stone. B: Mottle is a patchy colour defect, not a fissure. C: Shelly bars are patches of soft shell material inside stone, not fissures.
Shortcut
Vent = small opening, so small fissure or hollow = vent.
Common mistake
Choosing 'shakes' because it means cracks in timber.
Correct answer: D) vents