The proton. There are three main types of subatomic particles. Protons, Neutrons, and Electrons. Protons are positively charged and found in the nucleus. Neutrons are not charged at all, and found in the nucleus, and electrons are negatively charged and found outside the nucleus in regions known as orbitals.
Potassium is the 19th element so it is B
This is the reason why the path at which a ray of light strikes a prism is different to the path after emergence from the other side. There is a refraction of light ray when the light passes from one medium to another at angle. Its speed changes. The bend is in one direction if the material it enters is denser, and other direction if less dense. The amount of bending is different because of different wavelengths.
Weight = m (mass) * g (acceleration due to gravity)
g = 9.80 m/s^2
m = 2.5 kg = 2,500 g
Weight = 2,500 g * 9.80 m/s^2
Weight = 24,500 N