The correct answer is A. 2 to 5 per cent carbon.
Hard steel is a type of steel that contains a high percentage of carbon. The carbon content of hard steel ranges from 2 to 5 per cent, which is much higher than the carbon content of mild steel, which ranges from
0.05 to 0.25 per cent. The high carbon content of hard steel makes it very strong and durable. However, it also makes it more brittle and difficult to work with.Hard steel is used in a variety of applications, including tools, machinery, and weapons. It is also used in the construction of bridges and other structures that require a high degree of strength and durability.
The other options are incorrect because they do not represent the correct range of carbon content for hard steel. Option B, 0.5 to 1.5 per cent carbon, is the range of carbon content for medium-carbon steel. Option C, 0.1 to 0.4 per cent carbon, is the range of carbon content for low-carbon steel. Option D, 0.01 to 0.04 per cent carbon, is the range of carbon content for very low-carbon steel.