\"give the nuclear symbol for the isotope of gallium, ga, that contains 40 neutrons per atom.\".

The nuclear symbol of the isotopes of gallium where as the symbol must be determined according to its parts and they are the symbol of the element, the atomic number of the element and also the mass number of the specific isotopes. So the symbols is Ga 42 over 71 . I hope this would help

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