Question 1
In activity 17.3, in which tube do the gas bubbles come off fastest?
The right answer is the one marked above.
The tube given 7.5 ml of HCl acid. That is where the HCl is most concentrated — since all three tubes hold the same total volume, more acid means a higher concentration.
The pattern observed is a clear one: as the concentration rises in order, so does the rate of bubbling.