Answer:
See the answer below
Step-by-step explanation:
Increasing the concentration of the acid means that the number of ions/particles in the reaction vessel has increased. The higher the number of ions/particles, the higher the frequency of collision of these ions provided that the volume of the reactants remains unchanged.
It is just like comparing a densely populated area with a sparsely populated area. You are more likely to encounter people at a higher frequency in a densely populated area when compared to a sparsely populated area.