Why can't chemical changes be reversed? examples to explain

What kind of substance aquatic birds use to coat their feathers?

The double arrows tell you that the following reaction CO2 + H2O ⇄ H2 + CO3

A steady increase in global temperature has been recorded between 1900 and today. Before concluding that this rise in temperature is the result of the increased burning of fossil fuels, which of the following questions would have to be answered? A.

Which of the following is an example of observational scientific investigation mixing two reactants together in a small beaker drying a solid produced by placing it in an oven noting the color of a solution when heated < - - - i think maybe this one

The cell's nucleus is filled with a substance called protein.

What two factors combine to determine heart rate?

Recycling solid wastes is an example of

What is the name of the 3 disease causing microorganisms? (This is how the question is wrote on my homework and it doesn't make sense to me, sorry.)

This is a chemical process that uses light to process carbon dioxide in plants.

List at least three similarities between cellular respiration and photosynthesis