Read the following description of the element zinc and indicate which are physical properties and which are chemical properties. (a) zinc melts at 420 ∘c. (b) when zinc granules are added to dilute sulfuric acid, hydrogen is given off and the metal dissolves. (c) zinc has a hardness on the mohs scale of 2.5 and a density of 7.13 g/cm3 at 25 ∘c. (d) it reacts slowly with oxygen gas at elevated temperatures to form zinc oxide, zno.