Compare and contrast a mixture vs a compound and provide an example of each stating the identifiable characteristics. PLEASE HELP!!

Once similarity and one difference between a mixture of elements and a mixture of compounds

What is the pressure of 0.500 moles of carbon dioxide gas in a 2.5 l tank and at a temperature of 301 k? (r=0.0821 l·atm/mol·k) 3.08 atm 1.2 atm 0.23 atm 4.01 atm 4.94 atm

The molar mass of iron(fe) is 55.8 g/mol. what is the mass in grams of 2.25 moles of iron?