https://quizlet.com/17797282/periodicity-review-flash-cards/
i took a test like this and i went to this site /\ /\ /\ and the flash cards have the answers
CH4 + 2O2 =======> CO2 + 2H2O
........................................................................
Answer: 1.997 M
Explanation:
molarity = moles of solute/liters of solution or 
first we have to find our moles of solute (mol), which you can find by dividing the mass of solute by molar mass of solute
mass of solute: 92 g
molar mass of solute: 46.08 g/mol
let's plug it in:

next, we plug it into our original equation:

Because the copper roofs, have been outside for a while and oxidization has occurred.
When metals become oxidized they rust, but when copper becomes oxidized, it turns greenish.
So copper roofs oxidize and turn green from being outside and a copper square doesn’t if it’s inside.