Fictitious element jz has two common isotopes. three-fifth of the isotopes have a mass of 329.1 amu, while the rest have a mass of 334.5 amu. given this information what is the average atomic mass (in amu) of jz? report the answer to 4 significant figures

The average atomic mass of Jz is 331.3 u.

The average atomic mass of Jz is the weighted average of the atomic masses of its isotopes.

We multiply the atomic mass of each isotope by a number representing its relative importance (i.e., its fractional abundance).  

Thus,

⅗ × 329.1 u = 197.46  u

⅖ × 334.5 u = 133.80 u

      TOTAL = 331.3   u

do u have any choices to choose from ? ?

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.