Q1: Addition of __________ to steel does not impart hardness.

ANS:B - copper

Copper is sometimes added to steel in small amounts to enhance its properties. When copper is alloyed with steel, it can impart several beneficial characteristics:

1. Improved Corrosion Resistance: Copper can enhance the steel's resistance to corrosion, particularly in environments where corrosion is a concern. The presence of copper forms a protective oxide layer on the surface of the steel, which helps inhibit further corrosion.
2. Increased Strength: Copper can contribute to an increase in the strength of steel. It does so by solid-solution strengthening, which means that copper atoms occupy spaces within the steel's crystal lattice, hindering the movement of dislocations and making it more difficult for the steel to deform under stress.
3. Enhanced Electrical and Thermal Conductivity: Copper improves the electrical and thermal conductivity of steel. This can be advantageous in certain applications where conductivity is important, such as in electrical wiring or heat exchangers.
4. Improved Workability: Copper can also enhance the machinability and formability of steel, making it easier to work with during manufacturing processes such as machining, forging, and stamping.

It's important to note that the addition of copper to steel is typically done in controlled amounts, as excessive copper content can lead to negative effects such as reduced weldability and increased susceptibility to hydrogen embrittlement. Therefore, copper is used judiciously in steel alloys to achieve the desired balance of properties without compromising other important characteristics of the steel.