Q:

What happens when an acid or a base is mixed with water?

• 1
  Decrease in the concentration of ions (H2O+/OH–) per unit volume
• 2
  Decrease in the concentration of ions (H3O+/OH–) per litre volume 
• 3
  Increase in the concentration of ions (H3O+/OH–) per unit volume
• 4
  Decrease in the concentration of ions (H3O+/OH–) per unit