What percent of potassium-40 remains undecayed in a rock that is 3.9 billion years old? The 3.9 billion year old rock has undergone three half-lives (3.9 divided by 1.3 = 3). After 3 half-lives, 12.5% of the potassium-40 remains undecayed.
The statement which is false about the intergumentary system is option D. "Keratin is the pigment responsible for skin color."
Even though the skin color of human beings is affected y different substances, the pigment melanin is responsible for it. Melanin is produced within the skin in cells known as melanocytes and it determines of the skin color of darker-skinned humans.
For instance, the skin color of those who have light skin is determined primary by the bluish-white connective tissue placed beneath the dermis and by the hemoglobin which circulates in the veins of the dermis.
