According to boyle’s law, when the pressure on a gas increases at constant temperature, its volume
a.
increases.
b.
stays constant.
c.
decreases.
d.
increases, then decreases.

The answer is c. decreases. The gas law has a rule of P1V1=P2V2. So when the pressure of this gas increases, the volume will decrease.

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