How hard is concrete on mohs scale?

Oxygen has eight protons eight neutrons and eight electrons what is the atomic mass? What happens when you boil antioxidants? Damage caused by the tangshan earthquake? What is CD replication? What do you call lines of equal velocity? If muscle are not used they begin to to deteriorate this condion is known as? Who is the actor that looks like Patrick Dempsey and played in late 80's and early 90's teen movies with dark features and had a real resemblance to Patrick Dempsey and never made it that big? What is the process of placing sediment in a new place called? How many .75 cubic foot bags equals 16 cubic feet? If the temperature is low? What monomer makes up carbohydrate? Why does continental crusts stand higher on the mantle then oceanic crust? Why does a magnet rest at its north-south position? How do you purify impure DNA after restriction digestion? What makes galena smell? Why plants disperse their seeds as far away as possible? What causes a Stars brightness? How long has Stromboli been active? What do zinnia seeds look like? How do you charge a divoom itour 20?