Download Aptitude Crack
img not found img not found

Stoichiometry - Engineering

Q1:

A solution having a pH value of 5 is less acidic than the one having a pH value of 2 by a factor of

A 3

B 100

C 1000

D none of these

ANS:C - 1000

The pH scale is logarithmic, meaning that each unit change in pH represents a tenfold change in the concentration of hydrogen ions (𝐻+H+) in the solution. So, the difference in pH between 5 and 2 is 3 units. Therefore, the concentration of 𝐻+H+ ions in the solution with a pH of 2 is 1000 times greater than the concentration of 𝐻+H+ ions in the solution with a pH of 5. To clarify further:

  • If a solution has a pH of 2, the concentration of 𝐻+H+ ions is 10−210−2 M.
  • If a solution has a pH of 5, the concentration of 𝐻+H+ ions is 10−510−5 M.
The concentration of 𝐻+H+ ions in the solution with pH 2 is 10−210−2 M, which is 1000 times greater than the concentration of 𝐻+H+ ions in the solution with pH 5 (10−510−5 M). Therefore, the correct answer is: 1000