If scattering particles are 56 for 90° angle then this will be at 60° angle.

224

According to scattering formula

$N \propto \frac{1}{\sin ^4(\theta / 2)} \Rightarrow \frac{N_2}{N_1}=\left[\frac{\sin \left(\theta_1 / 2\right)}{\sin \left(\theta_2 / 2\right)}\right]^4$

$\Rightarrow \frac{N_2}{N_1}=\left[\frac{\sin \frac{90^{\circ}}{2}}{\sin \frac{60^{\circ}}{2}}\right]^4=\left[\frac{\sin 45^{\circ}}{\sin 30^{\circ}}\right]^4$

$\Rightarrow N_2=(\sqrt{2})^4 \times N_1=4 \times 56=224$