Tennessee Cosmetology Practice Exam

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Prepare for the Tennessee Cosmetology Exam with comprehensive review questions covering essential cosmetology principles. Enhance your knowledge, boost confidence, and increase your chances of passing the exam.

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What is the main ingredient in most hair relaxers?

Calcium hydroxide
Potassium hydroxide
Sodium hydroxide
Magnesium sulfate

The correct answer is: Sodium hydroxide

The main ingredient in most hair relaxers is sodium hydroxide. This chemical compound is highly effective in breaking down the disulfide bonds in hair, which allows the hair to become straighter and more manageable. Sodium hydroxide works through a process called "alkaline perm," where the high pH alters the hair’s structure. It is particularly favored for its effectiveness in straightening coarse or curly hair types. While other ingredients like calcium hydroxide and potassium hydroxide are also used in some relaxers, they are not as commonly used as sodium hydroxide for this purpose. Calcium hydroxide is often found in combination products, and potassium hydroxide is applied in less potent formulations; however, sodium hydroxide remains the most prevalent due to its strong efficacy. Magnesium sulfate, on the other hand, is typically associated with other hair treatments and is not used as a primary active ingredient in hair relaxers.