Acertain element x has four isotopes. 5.845% of x has a mass of 53.93961 amu. 91.75% of x has a mass of 55.93494 amu. 2.123% of x has a mass of 56.93539 amu. 0.2820% of x has a mass of 57.93328 amu. what is the average atomic mass of element x?

53.93961amu x .05845 = 3.152
55.93494 amu x .9175 = 51.320
56.93539 amu x .02123 = 1.208
57.93328 amu x .002820= .16633
add It up.
amu = 55.83833
round to significant figures
amu = 55.84

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃  → 3 nicl₂ + 2 albarium and copper bromideba + cubr  →  no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al  → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn  → znso₄ + na