Use a small paint brush or a wooden splinter to do this. Set the paper and the container aside where they will not be disturbed. Observe once an hour for the rest of the day and then again on the next day. Interpret your observations. Write word equations and formula equations for any reactions which you believe have occurred.
Crushed limestone is used in the blast furnaces which reduce iron ore to iron.
Identify the chemical processes which are used in drinking water treatment and in waste water treatment. Chlorine gas is commonly added to the water. A metal can made of iron left half buried in the ground will corrode to leave only a crumbled shell in a few years. A can made of aluminum half buried will last indefinitely. As copper weathers, it turns a dark brown and then various shades of green.