The emission of a beta particle has the effect a. decreasing mass by one unit /b. increasing mass by one unit / c. - no change in mass /d.- adding a proton to the nucleus / e. adding a proton of zero mass to the nucleus

The emission of a beta particle has the effect of : C. No change in mass

basically, beta particle has a very very little mass compared to the proton and  neutrons, so  little to the point that it never considered as a change in mass. But it does decreases the charge of atom

hope this helps

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