Answer:
Characteristic of a substance that Cannot be observed without altering the identity of the substance.
Explanation:
A physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance. Physical properties include color, density, hardness, and melting and boiling points.
hydrogen is the lightest element in the periodic table
Reflection, refracting, and the energy levels of molecular orbitals
What's the problem ? Hardness is not the definition of a metal.
You need to expand your thinking. EVERY element is solid, liquid, and gas, over different ranges of temperature ... including all of the metals. There are only TWO elements that are liquid AT ROOM TEMPERATURE, and mercury is one of them. But on a mild day at the south pole, mercury is solid too.
