Select the correct answer. A solution has a ph of 4. 20. Using the relationship between ph and poh, what is the concentration of oh−? a. 9. 9 × 10-1 m b. 6. 2 × 10-1 m c. 6. 3 × 10-5 m d. 6. 7 × 10-6 m e. 1. 6 × 10-10 m.

Layer r contains a well-known index fossil that is 100 million years old. based on this information and the principle of superposition, a. layers t and m are older than 100 million years, and layers x and g are younger than 100 million years. b. layers t, m, x, and g are all older than 100 million years. c. layers t and m are younger than 100 million years, and layers x and g are older than 100 million years.