pH Scale — Homi Bhabha Class 9 Chemistry MCQs with Solutions
Free Homi Bhabha Class 9 Chemistry pH Scale MCQs with step-by-step solutions (10 questions). Part of Acids, Bases & Salts. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — pH Scale · medium · theory
The pH scale is used to measure the ______ of a solution and ranges from:
A. temperature; 0 to 100
B. acidity or basicity; 0 to 14 ✓ Correct
C. mass; 0 to 7
D. density; 1 to 10
Solution: The pH scale (0–14) indicates how acidic or basic a solution is.
Q2 — pH Scale · medium · theory
A neutral solution such as pure water has a pH of:
A. 1
B. 7 ✓ Correct
C. 14
D. 0
Solution: Pure water is neutral with pH = 7.
Q3 — pH Scale · medium · theory
A solution with a pH of 3 is:
A. neutral
B. a salt solution
C. basic
D. acidic ✓ Correct
Solution: pH less than 7 means the solution is acidic.
Q4 — pH Scale · hard · theory
Of two solutions, one has pH 2 and the other pH 5. The more acidic solution is the one with pH:
A. 5
B. neither is acidic
C. both are equal
D. 2 ✓ Correct
Solution: Lower pH means greater acidity, so pH 2 is more acidic than pH 5.
Q5 — pH Scale · hard · theory
A solution turns red litmus blue. Its pH is most likely:
A. exactly 0
B. greater than 7 ✓ Correct
C. less than 7
D. exactly 7
Solution: Turning red litmus blue indicates a base, which has pH greater than 7.
Q6 — pH Scale · medium · theory
The pH of human blood is close to:
A. 0
B. 12 (strongly basic)
C. 2 (strongly acidic)
D. 7.4 (slightly basic) ✓ Correct
Solution: Blood is maintained at a slightly basic pH of about 7.4.
Q7 — pH Scale · easy · theory
On the pH scale, the pH of a neutral solution such as pure water at 25°C is:
A. 0
B. 1
C. 7 ✓ Correct
D. 14
Solution: A neutral solution has equal H+ and OH- ions and a pH of 7 at 25°C; below 7 is acidic and above 7 is basic.
Q8 — pH Scale · medium · theory
As a solution is made more and more acidic, what happens to its pH value and its hydrogen ion (H+) concentration?
A. pH decreases and H+ concentration decreases
B. pH decreases and H+ concentration increases ✓ Correct
C. pH increases and H+ concentration increases
D. pH stays at 7 while H+ concentration increases
Solution: A more acidic solution contains more H+ ions, and a higher H+ concentration corresponds to a lower pH value.
Q9 — pH Scale · medium · theory
The approximate pH values of four everyday liquids are: lemon juice 2, black coffee 5, pure water 7 and milk of magnesia 10. Which of these is basic (alkaline) in nature?
A. Black coffee
B. Milk of magnesia ✓ Correct
C. Pure water
D. Lemon juice
Solution: A pH above 7 is basic. Only milk of magnesia (pH 10) lies above 7; lemon juice and coffee are acidic and pure water is neutral.
Q10 — pH Scale · hard · numerical
Solution A has a pH of 3 and solution B has a pH of 6. The hydrogen ion concentration of solution A is how many times that of solution B?
A. 3 times
B. 30 times
C. 300 times
D. 1000 times ✓ Correct
Solution: Each unit drop in pH multiplies the H+ concentration by 10. A difference of 3 pH units means 10³ = 1000 times greater H+ concentration in A.