Q1: Addition of small amount of __________ to grey cast iron is done to produce nodular grey cast iron.

ANS:C - magnesium

The addition of a small amount of magnesium to grey cast iron is done to produce nodular grey cast iron. Explanation:

1. Manganese: Manganese is commonly used as an alloying element in various types of cast iron, including grey cast iron. However, manganese is not typically added specifically to produce nodular grey cast iron. It is more commonly added to improve the strength, hardness, and wear resistance of cast iron.
2. Phosphorous: Phosphorus is another alloying element commonly found in cast iron. However, its addition to grey cast iron is not typically associated with the production of nodular grey cast iron. Phosphorus can affect the microstructure and properties of cast iron, but it is not the primary element used to promote nodularization.
3. Magnesium: The addition of magnesium is essential for the production of nodular grey cast iron. Magnesium is added to the molten iron as a nodularizing agent, promoting the formation of graphite nodules within the cast iron microstructure. These nodules improve the mechanical properties of the cast iron, such as ductility, toughness, and fatigue strength.
4. Chromium: Chromium is occasionally used as an alloying element in cast iron to improve its corrosion resistance, wear resistance, and high-temperature properties. However, chromium is not typically added specifically for nodularization purposes in grey cast iron.