What example best illustrates the difference between a community and a population.

Which statement describes the phase change that occurs when dry ice is placed in an open container at room temperature?

An alloy contains 66 g of pure zinc. what is the percentage of zinc in the alloy? express your answer to two significant figures and include the appropriate units.

What is the wavelength of a 3*10^12 hz infrared wave a 3*10^20m b 1* 10^4m c 3*10^-3m d 1*10^-4 m