Rutherford found that a few $\alpha$-particles bounced back sharply. How does this single surprising result completely rule out Thomson's 'plum pudding model' of the atom? [Pg. No. 144]

Rutherford's observation that a few $\alpha$-particles bounced back sharply ruled out Thomson's plum pudding model because, in Thomson's model, the positive charge was thought to be spread uniformly throughout the atom. Such a spread-out positive charge could only cause small deflections, not a strong repulsion powerful enough to send heavy, fast-moving $\alpha$-particles backward. The sharp backward deflection showed that most of the positive charge and mass of the atom must be concentrated in a very small, dense region called the nucleus. Therefore, the atom could not be a uniform positively charged sphere with electrons embedded in it, as Thomson had proposed.