Answer:
When sulfurous, sulfuric, and nitric acids in polluted air and rain react with the calcite in marble and limestone, the calcite dissolves. In exposed areas of buildings and statues, we see roughened surfaces, removal of material, and loss of carved details. Stone surface material may be lost all over or only in spots that are more reactive.
Explanation:
You might expect that sheltered areas of stone buildings and monuments would not be affected by acid precipitation. However, sheltered areas on limestone and marble buildings and monuments show blackened crusts that have peeled off in some places, revealing crumbling stone beneath. This black crust is primarily composed of gypsum, a mineral that forms from the reaction between calcite, water, and sulfuric acid. Gypsum is soluble in water; although it can form anywhere on carbonate stone surfaces that are exposed to sulfur dioxide gas (SO2), it is usually washed away. It remains only on protected surfaces that are not directly washed by the rain.
Hey there!
Number 3, "has more people than ever before" is correct. As there are more people, there is a greater need more resources.
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Hormones -- such as melatonin and cortisol; the former signals the body to go to bed, while the latter signals for the sleeping person to wake up -- are created by physiological changes.
Answer:
6 water molecules (and technically sunlight/energy)
Explanation:
The inputs of photosynthesis are water and carbon dioxide (and energy); water is used in the light-dependent reactions, and carbon dioxide is used in the light-independent. The water has to be there to replace the lost electrons in the chlorophyll that leave the thylakoids after being excited by the solar energy.
<span>When frog matures from tadpole to adult, its gills are lost and develops functioning lungs. After maturity, frogs are still able to breathe through their skin---- known as “bimodal breathing,” wherein an animal uses two different systems for bringing in oxygen. These two different breathing systems allow adult frogs to shift between aquatic habitats (which require skin respiration) and land habitats (which are more suited to lung respiration).</span>
