When a constant force is applied to a particle, its acceleration...

According to Newton's second law of motion, the force applied on a particle is given by $F = ma$, where $m$ is the mass of the particle and $a$ is its acceleration.

Since the mass of a particle is constant, a constant force $F$ will produce a constant acceleration $a = \dfrac{F}{m}$.

Therefore, the acceleration of the particle will remain constant.