Which physical property is shown by scratching one material with another? malleability viscosity conductivity hardness

Malleability is the ability to be turned into thin wires (Incorrect) 
Viscosity is how thick or thin the substance is (Incorrect) 
Conductivity is the ability of the substance to pass electric current (Incorrect) 
Hardness is how easy it is to peel off or scratch a material with another (Correct) 

The physical property would be hardness. 

Hope I helped :) 

The correct answer is 7