The correct option is (b).
Explanation
A suspension is a heterogeneous mixture containing solid particles that are sufficiently large for sedimentation. Unlike solutions, the solute particles in a suspension do not dissolve but remain suspended throughout the bulk of the medium.
Statement 1 is Incorrect:
A suspension is a heterogeneous mixture, not homogeneous. The components do not mix uniformly, and the boundaries of separation between the particles and the medium are often visible.
Statement 2 is Correct:
In a suspension, the solute particles do not dissolve; they remain suspended throughout the bulk of the medium. These particles are unstable and will eventually settle down under the influence of gravity if left undisturbed.
Statement 3 is Incorrect:
The particles in a suspension are relatively large (typically larger than 100 nm or $10^{-5}$ cm). Consequently, they are large enough to be seen with the naked eye, unlike the particles in a true solution or a colloid.
Key Takeaway:
Suspensions are heterogeneous mixtures with large, visible particles that settle upon standing (unstable), whereas Colloids appear homogeneous but are heterogeneous with smaller particles, and Solutions are homogeneous mixtures with invisible particles.