Speed is the secular unit, which means it only measures "how fast it goes."

Velocity is a victory unit, which means it measures "both how fast it goes AND the direction."

Acceleration is the change of velocity over time.
Answer:
The correct option is 'c':electron,proton,helium nucleus
Explanation:
The De-Broglie's wavelength of particle is given by

Thus we can see that wavelength is inversely related to mass of the particle since 'h' (Plank's constant) and velocity is same for all the particles
Thus we conclude that the the lightest particle will have the most wavelength
Electron being the lightest of the 3 particles will have the largest wavelength thus the correct option is 'c'. Since electron has the largest wavelength followed by proton and the least wavelength among the 3 is of helium.
An atom is made up of three different particles, which are proton, neutron and electron. The proton and the neutron are located in the nucleus of the atom and they make up mass of the atom. The electron orbit around the nucleus. The proton is positively charged while the electron is negatively charged, thus, for the atom to remain neutral, the number of proton and electron in an atom must be equal. The neutron has no charge.
The atomic mass of an element = number of proton + number of neutron
Atomic mass of magnesium= 24
Number of proton = 12
Therefore, number of neutron = 24 - 12 = 12.
Thus, the number of neutron = 12.