The number of molecular collisions increases when B) more reactants are added.
Adding more reactants increases the concentration of molecules in a given volume, leading to a higher probability of collisions between the reactive molecules.
Here's a brief explanation of the other options:
- A) Products are removed: This can shift the equilibrium position according to Le Chatelier's principle but does not directly increase the number of collisions among reactants.
- C) The reaction temperature is lowered: Lowering the temperature generally decreases molecular motion and kinetic energy, leading to fewer collisions.
- D) The reacting molecules have an incorrect orientation upon impact: This statement implies that while collisions may occur, they are not effective in leading to a reaction if the orientation is incorrect. Thus, this also doesn't increase the number of effective collisions.
Therefore, option B is the best answer regarding the increase in molecular collisions.