Answer: Pigment.
Explanation: Our hair color is determined by two types of pigment, Eumelanins, and Pheomelanins. Which together produces all the natural hair colors we see every day with other people.
If It takes 60mL of 0.20M of sodium hydroxide (NaOH) to neutralize 25 mL of carbonic acid (
), then the concentration of the carbonic acid is 0.24M
The reaction between NaOH solution and
is written below

Volume of NaOH,
= 60 ml
Volume of
, 
Molarity of
, 
Molarity of NaOH, 
Number of moles of
, 
Number of moles of NaOH, 
The mathematical equation for neutralization reaction is:

Substitute
,
,
,
= 60ml, and
into the equation above in order to solve for 

Therefore, the concentration of the carbonic acid is 0.24M
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