Why does ice covered in sawdust not melt quickly?

There are several factors that contribute to ice covered in sawdust not melting quickly. However, the correct answer to this question is option 'C', which states that sawdust is a bad conductor of heat. Let's explore this in detail.

1. Sawdust as an insulator:
Sawdust is a poor conductor of heat, meaning it does not allow heat to transfer easily through its particles. This is due to the structure of sawdust, which consists of tiny wood particles with air pockets in between. The air pockets act as insulation, minimizing heat transfer between the ice and the surrounding environment.

2. Heat transfer by conduction:
When heat is applied to a solid object, it is transferred through conduction. In the case of ice covered in sawdust, the heat from the surroundings (such as room temperature) tries to transfer to the ice to melt it. However, sawdust acts as a barrier, inhibiting the transfer of heat through conduction. As a result, the ice covered in sawdust retains its solid state for a longer period.

3. Reduced surface area:
Sawdust, being a porous material, can absorb some of the water formed during the melting process. This absorption reduces the surface area of direct contact between the ice and the surrounding environment. With a smaller surface area exposed, the rate of heat transfer is further slowed down, leading to slower melting.

4. Insulation from air contact:
Sawdust also creates a layer of insulation between the ice and the surrounding air. As the ice covered in sawdust melts, the sawdust absorbs the water, preventing direct contact between the ice and the surrounding air. Since air is a good conductor of heat, the insulation provided by sawdust slows down the melting process.

In conclusion, the presence of sawdust on ice slows down the melting process due to its poor conductivity, the reduced surface area of contact, and the insulation it provides against heat transfer from the surrounding environment. Therefore, option 'C' is the correct answer.