If a particle's speed increases, what happens to its kinetic energy? its kinetic energy increases. its kinetic energy totally disappears. its kinetic energy decreases. its kinetic energy stays the same.

The answer should be its kinetic energy increases.

The kinetic energy of a particle means how fast they move, the faster they move, the more kenetic energy they have. In addition, when it moves faster and have more kenetic energy, their temperature becomes higher too.

Therefore, the answer is the first one.

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.