The timber having maximum resistance against white ants is obtained from ..........
Try it first: pick an option, then read the explanation.
Natural Durability and Insect Resistance
Some species of timber have a high natural durability, which includes resistance to decay and insect attack. This resistance often comes from the presence of natural chemicals, oils, and resins within the wood's heartwood that are toxic or repellent to insects like termites (white ants) and fungi.
Detailed Analysis of the Options
(a) Chir
Chir (Pine) is a softwood and is not naturally resistant to termites. It is highly susceptible to attack and requires chemical preservative treatment for any application where it might be exposed to insects.
(b) Shisham
Shisham (Indian Rosewood) is a durable hardwood and has a moderate level of resistance to termites. However, it is not considered as resistant as Teak.
(c) Sal
Sal is a very hard, heavy, and durable hardwood. It offers good resistance to decay and some resistance to termites, but it is not immune and can be attacked, especially the sapwood.
(d) Teak
This is the correct answer. Teak is renowned for its exceptional natural resistance to termites and other insects. The heartwood of the teak tree is rich in natural oils and silica. These compounds act as a powerful repellent, making the wood unpalatable and toxic to termites. This is why teak can be used in exterior applications, for shipbuilding, and even in direct contact with the ground with minimal risk of insect damage, making it one of the most durable and valuable timbers available.
Termite Resistance of Common Timbers
| Timber | Type | Natural Termite Resistance |
|---|---|---|
| Teak | Hardwood | Very High (due to natural oils) |
| Sal | Hardwood | Good to Moderate |
| Shisham | Hardwood | Moderate |
| Chir (Pine) | Softwood | Low (Susceptible) |
Study Tips
- Teak = Termite-Proof: For exam purposes, the key association is that Teak's natural oils make it the best choice for resisting termites.
- Natural Oils are Key: Understand that the reason for Teak's resistance is the presence of natural protective chemicals in its heartwood.
- Hardwood is Generally Better: Remember that hardwoods like Teak, Sal, and Shisham are generally more resistant to insects than softwoods like Pine.