Ba(OH)₂(aq) + 2HNO₃(aq) = Ba(NO₃)₂(aq) + 2H₂O(l)
At the reaction of barium hydroxide with nitric acid there are no visual changes.
Ba(OH)₂(aq) + H₂SO₄(aq) = BaSO₄(s) + 2H₂O
At the reaction of barium hydroxide with sulfuric acid the precipitat of white color is formed.
The organism was once a clam and most likely became a fossil after being buried by silt in its watery environment after death. Might need more clarification on what exact answer you need.
It would be B. DNA it contains the genetic information for synthesizing specific proteins and other structures that characterize a cell to be a particular cell.
Earth contains huge quantities of water in its oceans, lakes, rivers, the atmosphere, and believe it or not, in the rocks of the inner Earth. Over millions of years, much of this water is recycled between the inner Earth, the oceans and rivers, and the atmosphere. This cycling process means that freshwater is constantly made available to Earth's surface where we all live. Our planet is also very efficient at keeping this water. Water, as a vapor in our atmosphere, could potentially escape into space from Earth. But the water doesn't escape because certain regions of the atmosphere are extremely cold. (At an altitude of 15 kilometers, for example, the temperature of the atmosphere is as low as -60° Celsius!) At this frigid temperature, water forms solid crystals that fall back to Earth's surface.
Many people live faraway from freshwater sources. They need to carry their water home.
While our planet as a whole may never run out of water, it's important to remember that clean freshwater is not always available where and when humans need it. In fact, half of the world's freshwater can be found in only six countries. More than a billion people live without enough safe, clean water.
Also, every drop of water that we use continues through the water cycle. Stuff we put down the drain ends up in someone or something else's water. We can help protect the quality of our planet's freshwater by using it more wisely.