Developers have a pH of

Developers have a pH of

• A. 1-2
• B. 2.5-4.5
• C. 6-7
• D. 8-9

Answer: (B)

The main idea here is that developers used in hair color are mildly acidic. Hydrogen peroxide, the active ingredient in most developers, needs an acidic environment to stay stable and to oxidize the dye precursors effectively, which allows the color to develop. That’s why the typical developer pH sits in the range around 2.5 to 4.5. If the pH were much lower (very acidic) it could be overly harsh and unstable; if it were neutral or alkaline, the peroxide wouldn’t oxidize as efficiently, and the color development could be unpredictable or damage the hair. So the 2.5–4.5 range best fits the needs of stability and effective color development.