The presence of sulphur in pig iron makes

Answer: Option B

Correct Answer: B) It brittle

Pig iron is the raw material used to make steel.

Sulphur is an impurity that can be found in pig iron.

When too much sulphur is present, it makes the iron brittle, meaning it's more likely to crack or break when bent or stressed.

Let's look at why the other options are not the best answer:

A) It easily machinable: Sulphur can *sometimes* improve machinability in steel, but it usually doesn't in pig iron, and excessive sulphur makes it brittle not machinable.

C) It hard: While sulphur can affect hardness, its primary effect is to make the iron brittle.

D) The casting unsound: While high sulphur content *can* contribute to casting defects, the primary effect is that the resulting iron will be brittle even if the casting is good otherwise. Therefore, brittle is the better answer as this directly relates to the material's property.

So, the presence of sulphur in pig iron primarily makes it brittle.