Which term best describes a pure substance that is made up of only one type of atom

Which statement describes john tuzo wilson’s contribution to the theory of plate tectonics?

Cathy hypothesized that corn would not grow in mud. to test this hypothesis, she took corn kernels and placed 5 in mud, 3 in soil, and 2 in water. to her surprise, the kernels in the mud grew faster than the kernels in the soil. what error might have caused these unexpected results? a. wrong hypothesis b. not enough variables c. undefined control d. too many variables

What if the yeast were extremely active and produced more than 100ml gas. would you know? why/why not