A sound wave has a frequency of 2700Hz and wavelength of 20cm. What is it’s velocity?

1. crust 1 the metallic layer at the earth's center 2. inner core 3 the firm layer between the crust and the asthenosphere 3. lower mantle 2 the layer surrounding the inner core 4. asthenosphere 4 the semi-solid layer between the top layer and the upper mantle 5. upper mantle 5 the layer between the asthenosphere and lower mantle 6. top layer 6 the earth's outermost layer 7. outer core 7 the hottest part of the mantle

The us and canadian governments are doing all of the following to combat environmental problems except a. encouraging the use of public transportation b. enacting clean water policies c. requiring emissions testing d. limiting animal populations in some regions

How many structures do prokaryotic cells have in common with the eukaryotic cells? a. 2b. 3c. 4d. 5