Answer: Option D. -> High carbon
Cold chisels are made from carbon tool-steel, which is usually octagonal in cross-section.
Tool-steel is used as it can be hardened to form a hard and tough cutting edge.
To make a cold chisel heat the end of the bar of tool steel until it is bright red and hammer to the desired shape.

Answer: Option D. -> 2%
Cast iron is a ferrous alloy which has more than 2% carbon in it.
Though it can have any percentage of carbon between 2% to 6.67%, but practically it is in between 2% to 4% only.

Answer: Option A. -> Improves wear resistance, cutting ability and toughness
Chromium in steel Increases strength, hardness, hardenability, and toughness, as well as creep resistance and strength at elevated temperatures.
It improves machinability and resistance to corrosion and it intensifies the effects of other alloying elements.
In hot-work steels and high speed steels, it increases red-hardness properties.

Answer: Option D. -> All of these
Most of the world's steel is produced by the electric-arc method, which uses high-current electric arcs to melt steel scrap and convert it into liquid steel of specified chemical composition and temperature.
This process is adapted to Alloy and carbon tool steel and Magnet steel and High speed tool steel

Answer: Option D. -> 0.8%
Eutectoid steel contains 0.8% of carbon

Answer: Option D. -> 3.5 to 4.5%
Pig Iron
Chemical Composition: C: 3.5 - 4.5%, Mn: 0.4 - 1.0%, Si: 0.5 - 1.2%, P: 0.15% Max, S: 0.04% Max.

Answer: Option C. -> 1 to 5%
Pig Iron
Chemical Composition: C: 3.5 - 4.5%, Mn: 0.4 - 1.0%, Si: 0.5 - 1.2%, P: 0.15% Max, S: 0.04% Max.

Answer: Option D. -> 1.7 to 4.5
Cast iron is a ferrous alloy which has more than 2% carbon in it. Though it can have any percentage of carbon between 2% to 6.67%, but practically it is in between 2% to 4% only.

Answer: Option A. -> Hardness
High silicon iron-based alloys are excellent corrosion resistant materials with advantages of superior corrosion resistant properties, low cost and saving on noble metals such as nickel and chromium.
When containing 14.5% or more silicon, the corrosion resistance of these iron-based alloys is better than that of some cast irons containing a significant amount of chromium, nickel and/or molybdenum, and even than that of certain nickel based alloys in some severe corrosion conditions.

Answer: Option C. -> Manganese
Manganese increases hardenability and tensile strength of steel, but to a lesser extent than carbon.
It is also able to decrease the critical cooling rate during hardening, thus increasing the steels hardenability much more efficient than any other alloying elements.
Manganese is used to make the blades of bulldozers, bucket wheel excavators and other earth moving equipment contain iron.