An unknown radioactive element appears to have a half-life of 5.0 minutes. How much of a 2.0000 gram sample will remain undecayed after 20 minutes?

How many moles of oxygen react with 12 moles of aluminum

Answer asap need by wednesday morning explain how a buffer works, using an ethanoic acid/sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.

Nh4no3 n2o + 2h2o a chemist who is performing this reaction starts with 160.1 g of nh4no3. the molar mass of nh4no3 is 80.03 g/mol; the molar mass of water (h2o) is 18.01 g/mol. what mass, in grams, of h2o is produced?