When alpha particles are sent through a thin metal foil, most of them go straight through the foil because :
most part of the atom is empty space
alpha particles move with high velocity
Do you know what did Rutherford observed when he carried out α-scattering experiment?
Rutherford observed that
(a) Most of the α-particles ( 99%) passed through the gold foil undeflected.
(b) A small fraction of the α-particles was deflected by small angles.
(c) A very few α-particles (1 in 20,000) bounced back, that is, they were deflected by nearly 180∘.
Therefore, option (a) (b) and (c) are correct.
Why did most of α-particle go straight through the foil?
⇒ yes, by that observation he concluded that most of the space in an atom is empty.
And alpha particles move with high velocity that's why they didn't interact with an electron most of the time.
Therefore, option (c) and (d) are correct.