Statement-1: For the scattering of $\alpha$-particles at large angles, only the nucleus of the atom is responsible.

Statement-2: Nucleus is very heavy in comparison to electrons.

We know that an electron is very light particle as compared to an $\alpha$-particle. Hence electron cannot scatter the $\alpha$-particle at large angles, according to law of conservation of momentum. On the other hand, mass of nucleus is large and positively charged, hence only the nucleus of atom is responsible for scattering of $\alpha$-particles.