Which rock type appeared first on earth? why?

The pattern of this wave changes between its beginning and end. what is true about the amplitude and wavelength of the wave when the pattern changes?

Long term exposure to waves can cause sunburns and skin cancer.

Which of the following is an advantage of using embryonic stem cells in medical research? a. the use of embryonic stem cells is much less expensive than the use of adult stem cells. o b. no living tissue is damaged when scientists use embryonic stem cells. o c. embryonic stem cells are able to differentiate into a wider range of cells than adult stem cells. d. there is no controversy surrounding the use of embryonic stem cells.