Why are some mystery elements easier to identify than other?

Astone dropped into a well is heard to strike the water after 8seconds. find the depth of the well if the velocity of sound is 350m/s

How many molecules are present in 3 mols of silicon dioxide (sio2)?

Urgent pls a. coal consumption levels off and remains flat. b. petroleum, natural gas, and renewables show an increase in consumption c. more nonrenewable resources continued to be consumed than renewable. d. there is little projected increase in nuclear energy use. e. carbon dioxide emissions are projected to decline as we approach 2040. global energy consumption is defined as the total energy used by an individual or organizations from around the world. use the graph above to analyze the projected energy consumption from now until 2040. which statements in the prompt apply? a) a, b, d b) b, c, d c) a, c, d d) a, b, c, d