The final speed of the green ball : 8.5 m/s
<h3>Further explanation</h3>
Given
mass of Croquet ball = 0.5 kg
v₁= 10 m/s
v₁'= 1.5 m/s
Required
the final speed
Solution
The law of conservation of momentum
m₁v₁ + m₂v₂ = m₁v₁ '+ m₂v₂' (1=red croquet ball, 2=green croquet ball)
v₂=0 (at rest)
Input the value :

Answer:
first ionization energy is the amount of energy required to remove an electron from isolated gaseous atom
so when atomic no increase across aperiod the ionization energy become lower
it's my opinion am not sure ok