Gallum: Z = 31
electron configuration: [Ar] 4s^2 3d10 4s2 4p1
Highest energy electron: 4p1
Quantum numbers:
n = 4, because it is the shell number
l = 1, it corresponds to type p orbital
ml = may be -1, or 0, or +1, depending on space orientation, they correspond to px, py, pz
ms = may be -1/2 or +1/2, this is the spin number.
Answer: E. none of these
Explanation: because the f-block element is n-2
TLDR: The kinetic energy is determined to be zero.
Kinetic energy is energy of motion; when an object is moving (i.e. it has speed or velocity), it has some amount of kinetic energy. The equation itself looks like so:
KE=1/2(m)(v)^2,
where "m" represents the mass of the object and "v" represents the objects speed or velocity. In this example, the ball has stopped, meaning it has no speed/velocity. This means that the final kinetic energy is determined to be zero or none, due to the lack of motion. Mathematically, you can see this by substituting "0" in for "v" (the ball is stopped):
KE=1/2(m)(v)^2
KE=1/2(m)(0)^2
KE=1/2(m)*0
KE=1/2*0
KE=0 J,
or zero kinetic energy.
Hope this helps! :)