Give a critical discussion on why hardness test needs to perform in engineering practice.
b) discuss 2 possible source of errors (other than parallax error) and how it's can effect the result.

Dis the

The answer is 12, for the points

Is there any opitions? if you have the periodic table, the noble gases are 8a family, the halogen are the 7a family, and the nonmetal are  carbon, nitrogen, phosphorus, oxygen, sulfur, selenium, fluorine, chlorine, bromine, iodine and astatine.