Changing the concentration of one or more of the reactants can affect the rate of a reaction. This is TRUE, as it means there are more collisions between particles and therefore a higher probability of successful collisions, which speeds the reaction up.
Using the reactants in a fine, powder form rather than a large, chunky form will increase the rate of a chemical reaction as the surface area of the reactants will increase. Therefore, there is a higher probability of successful collisions, which speeds the reaction up.
A catalyst works by increasing the activation energy needed for a reaction. This is TRUE, and the catalyst itself is not used up.
Sorry I couldn't get back to you earlier. I usually use the Brainly app so am unable to check comments on my wall.
