Question

What is the normal pH range of human blood?

• A. 4.0-4.5
• B. 6.45-6.55
• C. 7.35-7.45
• D. 8.25-8.35

Hint:

Blood is kept slightly on the basic side of neutral.

Answer 1

The Correct Option is C

Step 1: Recall what pH measures.
pH tells us how acidic or basic a solution is on a scale from 0 to 14, where 7 is neutral, values below 7 are acidic, and values above 7 are basic or alkaline.

Step 2: Recall the normal pH of human blood.
Human blood is kept slightly on the basic side of neutral, and the body tightly controls it within a narrow range of 7.35 to 7.45 using buffers in the blood, the lungs, and the kidneys. Even a small shift outside this range can seriously affect how enzymes and cells work.

Step 3: Rule out the other options.
A range of 4.0 to 4.5 is strongly acidic, far too low for blood, and would be fatal if it occurred. A range of 6.45 to 6.55 is slightly acidic and still below the true blood pH range. A range of 8.25 to 8.35 is too basic and also outside the safe limit the body maintains.

Step 4: Final answer.
The normal pH range of human blood is 7.35 to 7.45.
\[ \boxed{7.35\text{-}7.45} \]